diff --git a/.lintr b/.lintr
index 9c43293db..4656a8ddc 100644
--- a/.lintr
+++ b/.lintr
@@ -5,6 +5,7 @@ linters: with_defaults(
     object_name_linter = object_name_linter(c("snake_case", "CamelCase")), # only allow snake case and camel case object names
     cyclocomp_linter = NULL, # do not check function complexity
     commented_code_linter = NULL, # allow code in comments
-    line_length_linter = line_length_linter(180)
+    line_length_linter = line_length_linter(180),
+    indentation_linter(indent = 2L, hanging_indent_style = "never")
     )
 
diff --git a/DESCRIPTION b/DESCRIPTION
index 1f1248aa7..6a209ec99 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -73,7 +73,7 @@ Config/testthat/edition: 3
 Config/testthat/parallel: false
 NeedsCompilation: no
 Roxygen: list(markdown = TRUE, r6 = TRUE)
-RoxygenNote: 7.2.3
+RoxygenNote: 7.2.3.9000
 Collate:
     'mlr_reflections.R'
     'BenchmarkResult.R'
diff --git a/NAMESPACE b/NAMESPACE
index 42587fb0d..1e4db46ba 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -234,6 +234,8 @@ import(palmerpenguins)
 import(paradox)
 importFrom(R6,R6Class)
 importFrom(R6,is.R6)
+importFrom(data.table,as.data.table)
+importFrom(data.table,data.table)
 importFrom(future,nbrOfWorkers)
 importFrom(future,plan)
 importFrom(graphics,plot)
diff --git a/R/DataBackend.R b/R/DataBackend.R
index 948a12fb0..c61c28110 100644
--- a/R/DataBackend.R
+++ b/R/DataBackend.R
@@ -98,6 +98,7 @@ DataBackend = R6Class("DataBackend", cloneable = FALSE,
       }
       private$.hash = assert_string(rhs)
     },
+
     #' @template field_col_hashes
     col_hashes = function() {
       cn = setdiff(self$colnames, self$primary_key)
diff --git a/R/Resampling.R b/R/Resampling.R
index 8e43d7119..e03d4c371 100644
--- a/R/Resampling.R
+++ b/R/Resampling.R
@@ -82,9 +82,6 @@
 #' prop.table(table(task$truth(r$train_set(1)))) # roughly same proportion
 Resampling = R6Class("Resampling",
   public = list(
-    #' @template field_id
-    id = NULL,
-
     #' @template field_label
     label = NULL,
 
@@ -126,7 +123,7 @@ Resampling = R6Class("Resampling",
     #'
     #' Note that this object is typically constructed via a derived classes, e.g. [ResamplingCV] or [ResamplingHoldout].
     initialize = function(id, param_set = ps(), duplicated_ids = FALSE, label = NA_character_, man = NA_character_) {
-      self$id = assert_string(id, min.chars = 1L)
+      private$.id = assert_string(id, min.chars = 1L)
       self$label = assert_string(label, na.ok = TRUE)
       self$param_set = assert_param_set(param_set)
       self$duplicated_ids = assert_flag(duplicated_ids)
@@ -186,6 +183,7 @@ Resampling = R6Class("Resampling",
         instance = private$.combine(lapply(strata$row_id, private$.sample, task = task))
       }
 
+      private$.hash = NULL
       self$instance = instance
       self$task_hash = task$hash
       self$task_nrow = task$nrow
@@ -214,6 +212,16 @@ Resampling = R6Class("Resampling",
   ),
 
   active = list(
+    #' @template field_id
+    id = function(rhs) {
+      if (missing(rhs)) {
+        return(private$.id)
+      }
+
+      private$.hash = NULL
+      private$.id = assert_string(rhs, min.chars = 1L)
+    },
+
     #' @field is_instantiated (`logical(1)`)\cr
     #'   Is `TRUE` if the resampling has been instantiated.
     is_instantiated = function(rhs) {
@@ -227,11 +235,18 @@ Resampling = R6Class("Resampling",
       if (!self$is_instantiated) {
         return(NA_character_)
       }
-      calculate_hash(list(class(self), self$id, self$param_set$values, self$instance))
+
+      if (is.null(private$.hash)) {
+        private$.hash = calculate_hash(list(class(self), self$id, self$param_set$values, self$instance))
+      }
+
+      private$.hash
     }
   ),
 
   private = list(
+    .id = NULL,
+    .hash = NULL,
     .groups = NULL,
 
     .get_set = function(getter, i) {
diff --git a/R/Task.R b/R/Task.R
index dd8f0a09c..cc2910607 100644
--- a/R/Task.R
+++ b/R/Task.R
@@ -48,7 +48,7 @@
 #'   Instead, the methods first create a new [DataBackendDataTable] from the provided new data, and then
 #'   merge both backends into an abstract [DataBackend] which merges the results on-demand.
 #' * `rename()` wraps the [DataBackend] of the Task in an additional [DataBackend] which deals with the renaming. Also updates `$col_roles` and `$col_info`.
-#' * `set_levels()` updates the field `col_info()`.
+#' * `set_levels()` and `droplevels()` `update the field `col_info()`.
 #'
 #' @template seealso_task
 #' @concept Task
@@ -73,9 +73,6 @@
 #' head(task)
 Task = R6Class("Task",
   public = list(
-    #' @template field_id
-    id = NULL,
-
     #' @template field_label
     label = NA_character_,
 
@@ -114,7 +111,7 @@ Task = R6Class("Task",
     #'
     #' Note that this object is typically constructed via a derived classes, e.g. [TaskClassif] or [TaskRegr].
     initialize = function(id, task_type, backend, label = NA_character_, extra_args = list()) {
-      self$id = assert_string(id, min.chars = 1L)
+      private$.id = assert_string(id, min.chars = 1L)
       self$label = assert_string(label, na.ok = TRUE)
       self$task_type = assert_choice(task_type, mlr_reflections$task_types$type)
       if (!inherits(backend, "DataBackend")) {
@@ -175,7 +172,7 @@ Task = R6Class("Task",
       catf("%s (%i x %i)%s", format(self), self$nrow, self$ncol,
         if (is.null(self$label) || is.na(self$label)) "" else paste0(": ", self$label))
 
-      roles = self$col_roles
+      roles = private$.col_roles
       roles = roles[lengths(roles) > 0L]
 
       # print additional columns as specified in reflections
@@ -204,7 +201,7 @@ Task = R6Class("Task",
         catn(str_indent(sprintf("* %s:", str), roles[[role]]))
       })
 
-      nrows = list(test = length(self$row_roles$test), holdout = length(self$row_roles$holdout))
+      nrows = list(test = length(private$.row_roles$test), holdout = length(private$.row_roles$holdout))
       if (nrows$test || nrows$holdout) {
         str = paste(c(
           if(nrows$test) sprintf("%i (test)", nrows$test),
@@ -237,8 +234,8 @@ Task = R6Class("Task",
       assert_choice(data_format, self$data_formats)
       assert_flag(ordered)
 
-      row_roles = self$row_roles
-      col_roles = self$col_roles
+      row_roles = private$.row_roles
+      col_roles = private$.col_roles
 
       if (is.null(rows)) {
         rows = row_roles$use
@@ -368,6 +365,7 @@ Task = R6Class("Task",
     filter = function(rows) {
       assert_has_backend(self)
       rows = assert_row_ids(rows)
+      private$.hash = NULL
       private$.row_roles$use = intersect(private$.row_roles$use, rows)
       invisible(self)
     },
@@ -387,6 +385,8 @@ Task = R6Class("Task",
       assert_has_backend(self)
       assert_character(cols)
       assert_subset(cols, private$.col_roles$feature)
+      private$.hash = NULL
+      private$.col_hashes = NULL
       private$.col_roles$feature = intersect(private$.col_roles$feature, cols)
       invisible(self)
     },
@@ -452,7 +452,7 @@ Task = R6Class("Task",
 
       # columns with these roles must be present in data
       mandatory_roles = c("target", "feature", "weight", "group", "stratum", "order")
-      mandatory_cols = unlist(self$col_roles[mandatory_roles], use.names = FALSE)
+      mandatory_cols = unlist(private$.col_roles[mandatory_roles], use.names = FALSE)
       missing_cols = setdiff(mandatory_cols, data$colnames)
       if (length(missing_cols)) {
         stopf("Cannot rbind data to task '%s', missing the following mandatory columns: %s", self$id, str_collapse(missing_cols))
@@ -484,9 +484,10 @@ Task = R6Class("Task",
       tab[, c("type_y", "levels_y") := list(NULL, NULL)]
 
       # everything looks good, modify task
+      private$.hash = NULL
       self$backend = DataBackendRbind$new(self$backend, data)
       self$col_info = tab[]
-      self$row_roles$use = c(self$row_roles$use, data$rownames)
+      private$.row_roles$use = c(private$.row_roles$use, data$rownames)
 
       invisible(self)
     },
@@ -535,7 +536,10 @@ Task = R6Class("Task",
       setkeyv(self$col_info, "id")
 
       # add new features
-      self$col_roles$feature = union(self$col_roles$feature, setdiff(data$colnames, c(pk, self$col_roles$target)))
+      private$.hash = NULL
+      private$.col_hashes = NULL
+      col_roles = private$.col_roles
+      private$.col_roles$feature = union(col_roles$feature, setdiff(data$colnames, c(pk, col_roles$target)))
 
       # update backend
       self$backend = DataBackendCbind$new(self$backend, data)
@@ -562,9 +566,11 @@ Task = R6Class("Task",
     #' the object in its previous state.
     rename = function(old, new) {
       assert_has_backend(self)
+      private$.hash = NULL
+      private$.col_hashes = NULL
       self$backend = DataBackendRename$new(self$backend, old, new)
       setkeyv(self$col_info[old, ("id") := new, on = "id"], "id")
-      self$col_roles = map(self$col_roles, map_values, old = old, new = new)
+      private$.col_roles = map(private$.col_roles, map_values, old = old, new = new)
       invisible(self)
     },
 
@@ -593,7 +599,10 @@ Task = R6Class("Task",
     set_row_roles = function(rows, roles = NULL, add_to = NULL, remove_from = NULL) {
       assert_has_backend(self)
       assert_subset(rows, self$backend$rownames)
+
+      private$.hash = NULL
       private$.row_roles = task_set_roles(private$.row_roles, rows, roles, add_to, remove_from)
+
       invisible(self)
     },
 
@@ -622,8 +631,12 @@ Task = R6Class("Task",
     set_col_roles = function(cols, roles = NULL, add_to = NULL, remove_from = NULL) {
       assert_has_backend(self)
       assert_subset(cols, self$col_info$id)
+
+      private$.hash = NULL
+      private$.col_hashes = NULL
       new_roles = task_set_roles(private$.col_roles, cols, roles, add_to, remove_from)
       private$.col_roles = task_check_col_roles(self, new_roles)
+
       invisible(self)
     },
 
@@ -646,6 +659,8 @@ Task = R6Class("Task",
 
       tab = enframe(lapply(levels, unname), name = "id", value = "levels")
       tab$fix_factor_levels = TRUE
+
+      private$.hash = NULL
       self$col_info = ujoin(self$col_info, tab, key = "id")
 
       invisible(self)
@@ -670,6 +685,7 @@ Task = R6Class("Task",
       tab = tab[lengths(levels) > lengths(new_levels)]
       tab[, c("levels", "fix_factor_levels") := list(Map(intersect, levels, new_levels), TRUE)]
 
+      private$.hash = NULL
       self$col_info = ujoin(self$col_info, remove_named(tab, "new_levels"), key = "id")
 
       invisible(self)
@@ -706,12 +722,27 @@ Task = R6Class("Task",
   ),
 
   active = list(
+    #' @template field_id
+    id = function(rhs) {
+      if (missing(rhs)) {
+        return(private$.id)
+      }
+
+      private$.hash = NULL
+      private$.id = assert_string(rhs, min.chars = 1L)
+    },
+
+
     #' @template field_hash
     hash = function(rhs) {
-      private$.hash %??% calculate_hash(
-        class(self), self$id, self$backend$hash, self$col_info,
-        remove_named(private$.row_roles, "test"), private$.col_roles, private$.properties
-      )
+      if (is.null(private$.hash)) {
+        private$.hash = calculate_hash(
+          class(self), self$id, self$backend$hash, self$col_info,
+          remove_named(private$.row_roles, "test"), private$.col_roles, private$.properties
+        )
+      }
+
+      private$.hash
     },
 
     #' @field row_ids (`integer()`)\cr
@@ -728,7 +759,7 @@ Task = R6Class("Task",
     #' * `"row_name"` (`character()`).
     row_names = function(rhs) {
       assert_ro_binding(rhs)
-      nn = self$col_roles$name
+      nn = private$.col_roles$name
       if (length(nn) == 0L) {
         return(NULL)
       }
@@ -804,6 +835,7 @@ Task = R6Class("Task",
       assert_names(names(rhs), "unique", permutation.of = mlr_reflections$task_row_roles, .var.name = "names of row_roles")
       rhs = map(rhs, assert_row_ids, .var.name = "elements of row_roles")
 
+      private$.hash = NULL
       private$.row_roles = rhs
     },
 
@@ -835,6 +867,8 @@ Task = R6Class("Task",
       assert_names(names(rhs), "unique", must.include = mlr_reflections$task_col_roles[[self$task_type]], .var.name = "names of col_roles")
       assert_subset(unlist(rhs, use.names = FALSE), setdiff(self$col_info$id, self$backend$primary_key), .var.name = "elements of col_roles")
 
+      private$.hash = NULL
+      private$.col_hashes = NULL
       private$.col_roles = task_check_col_roles(self, rhs)
     },
 
@@ -982,11 +1016,15 @@ Task = R6Class("Task",
 
     #' @template field_col_hashes
     col_hashes = function() {
-      private$.col_hashes %??% self$backend$col_hashes[setdiff(unlist(self$col_roles), self$backend$primary_key)]
+      if (is.null(private$.col_hashes)) {
+        private$.col_hashes = self$backend$col_hashes[setdiff(unlist(private$.col_roles), self$backend$primary_key)]
+      }
+      private$.col_hashes
     }
   ),
 
   private = list(
+    .id = NULL,
     .properties = NULL,
     .col_roles = NULL,
     .row_roles = NULL,
@@ -995,7 +1033,6 @@ Task = R6Class("Task",
 
     deep_clone = function(name, value) {
       # NB: DataBackends are never copied!
-      # TODO: check if we can assume col_info to be read-only
       if (name == "col_info") copy(value) else value
     }
   )
diff --git a/man/Resampling.Rd b/man/Resampling.Rd
index 134ab77b2..d48ab4aeb 100644
--- a/man/Resampling.Rd
+++ b/man/Resampling.Rd
@@ -105,10 +105,6 @@ Other Resampling:
 \section{Public fields}{
 \if{html}{\out{<div class="r6-fields">}}
 \describe{
-\item{\code{id}}{(\code{character(1)})\cr
-Identifier of the object.
-Used in tables, plot and text output.}
-
 \item{\code{label}}{(\code{character(1)})\cr
 Label for this object.
 Can be used in tables, plot and text output instead of the ID.}
@@ -144,6 +140,10 @@ Defaults to \code{NA}, but can be set by child classes.}
 \section{Active bindings}{
 \if{html}{\out{<div class="r6-active-bindings">}}
 \describe{
+\item{\code{id}}{(\code{character(1)})\cr
+Identifier of the object.
+Used in tables, plot and text output.}
+
 \item{\code{is_instantiated}}{(\code{logical(1)})\cr
 Is \code{TRUE} if the resampling has been instantiated.}
 
diff --git a/man/Task.Rd b/man/Task.Rd
index 187eaefe5..da405c0c2 100644
--- a/man/Task.Rd
+++ b/man/Task.Rd
@@ -46,7 +46,7 @@ This provides a different "view" on the data without altering the data itself.
 Instead, the methods first create a new \link{DataBackendDataTable} from the provided new data, and then
 merge both backends into an abstract \link{DataBackend} which merges the results on-demand.
 \item \code{rename()} wraps the \link{DataBackend} of the Task in an additional \link{DataBackend} which deals with the renaming. Also updates \verb{$col_roles} and \verb{$col_info}.
-\item \code{set_levels()} updates the field \code{col_info()}.
+\item \code{set_levels()} and \code{droplevels()} \verb{update the field }col_info()`.
 }
 }
 
@@ -108,10 +108,6 @@ Other Task:
 \section{Public fields}{
 \if{html}{\out{<div class="r6-fields">}}
 \describe{
-\item{\code{id}}{(\code{character(1)})\cr
-Identifier of the object.
-Used in tables, plot and text output.}
-
 \item{\code{label}}{(\code{character(1)})\cr
 Label for this object.
 Can be used in tables, plot and text output instead of the ID.}
@@ -153,6 +149,10 @@ Package version of \code{mlr3} used to create the task.}
 \section{Active bindings}{
 \if{html}{\out{<div class="r6-active-bindings">}}
 \describe{
+\item{\code{id}}{(\code{character(1)})\cr
+Identifier of the object.
+Used in tables, plot and text output.}
+
 \item{\code{hash}}{(\code{character(1)})\cr
 Hash (unique identifier) for this object.}
 
diff --git a/tests/testthat/test_Measure.R b/tests/testthat/test_Measure.R
index 38bd54134..312f10711 100644
--- a/tests/testthat/test_Measure.R
+++ b/tests/testthat/test_Measure.R
@@ -128,5 +128,5 @@ test_that("time_train is > 0", {
   skip_on_cran()
   rr = resample(tsk("iris"), lrn("classif.debug"), rsmp("holdout"))
   res = rr$score(msr("time_train"))
-  expect_gt(res$time_train, 0)
+  expect_gte(res$time_train, 0)
 })