diff --git a/nevergrad/optimization/base.py b/nevergrad/optimization/base.py
index 84b5801db..082ce33d4 100644
--- a/nevergrad/optimization/base.py
+++ b/nevergrad/optimization/base.py
@@ -4,6 +4,7 @@
 # LICENSE file in the root directory of this source tree.
 
 import pickle
+import logging
 import warnings
 from pathlib import Path
 from numbers import Real
@@ -26,7 +27,8 @@
 X = tp.TypeVar("X", bound="Optimizer")
 Y = tp.TypeVar("Y")
 IntOrParameter = tp.Union[int, p.Parameter]
-_PruningCallable = tp.Callable[[utils.Archive[utils.MultiValue]], utils.Archive[utils.MultiValue]]
+_PruningCallable = tp.Callable[[utils.Archive[utils.MultiValue]], None]
+logger = logging.getLogger(__name__)
 
 
 def _loss(param: p.Parameter) -> float:
@@ -404,18 +406,23 @@ def _update_archive_and_bests(self, candidate: p.Parameter, loss: tp.FloatLoss)
             )
         if np.isnan(loss) or loss == np.inf:
             self._warn(f"Updating fitness with {loss} value", errors.BadLossWarning)
-        mvalue: tp.Optional[utils.MultiValue] = None
+        mvalue = utils.MultiValue(candidate, loss, reference=self.parametrization)
+        if not self.archive.is_delegated:
+            # print(f"Updating archive for {candidate.uid[:8]} in {self.__class__.__name__}")
+            if x not in self.archive:
+                self.archive[x] = mvalue
+            else:  # reevaluation: needs updating
+                mvalue = self.archive[x]
+                mvalue.add_evaluation(loss)
+                # both parameters should be non-None
+                if mvalue.parameter.loss > candidate.loss:  # type: ignore
+                    mvalue.parameter = candidate  # keep best candidate
+        # the following should not happen since delegating archives are used afterwards
         if x not in self.archive:
-            self.archive[x] = utils.MultiValue(candidate, loss, reference=self.parametrization)
-        else:
-            mvalue = self.archive[x]
-            mvalue.add_evaluation(loss)
-            # both parameters should be non-None
-            if mvalue.parameter.loss > candidate.loss:  # type: ignore
-                mvalue.parameter = candidate  # keep best candidate
+            logger.warning("Archive is not correctly filled, please open an issue.")
+        mvalue = self.archive.get(x, mvalue)  # type: ignore  # update with master archive
         # update current best records
         # this may have to be improved if we want to keep more kinds of best losss
-
         for name in self.current_bests:
             if mvalue is self.current_bests[name]:  # reboot
                 best = min(self.archive.values(), key=lambda mv, n=name: mv.get_estimation(n))  # type: ignore
@@ -432,8 +439,9 @@ def _update_archive_and_bests(self, candidate: p.Parameter, loss: tp.FloatLoss)
                 #                  max(v.get_estimation(name) for v in self.archive.values()))
                 #         raise RuntimeError(f"Best value should exist in the archive at num_tell={self.num_tell})\n"
                 #                            f"Best value is {bval} and archive is within range {avals} for {name}")
-        if self.pruning is not None:
-            self.archive = self.pruning(self.archive)
+        if self.pruning is not None and not self.archive.is_delegated:
+            self.pruning(self.archive)
+            self.archive[x] = mvalue  # we must make sure that the current point is available for suboptim
 
     def ask(self) -> p.Parameter:
         """Provides a point to explore.
diff --git a/nevergrad/optimization/optimizerlib.py b/nevergrad/optimization/optimizerlib.py
index 955d0ff1e..17b74c892 100644
--- a/nevergrad/optimization/optimizerlib.py
+++ b/nevergrad/optimization/optimizerlib.py
@@ -1049,6 +1049,7 @@ def __init__(
     ) -> None:
         super().__init__(parametrization, budget=budget, num_workers=num_workers)
         self._optimizer = base_optimizer(self.parametrization, budget=budget, num_workers=num_workers)
+        # cannot delegate the archive since the parametrization is different :(
         self._subcandidates: tp.Dict[str, p.Parameter] = {}
         if scale is None:
             assert self.budget is not None, "Either scale or budget must be known in _Rescaled."
@@ -1374,6 +1375,8 @@ def __init__(
                     num_workers=sub_workers,
                 )
             )
+        for optim in self.optims:
+            optim.archive.delegate_to(self.archive)
         # current optimizer choice
         self._selected_ind: tp.Optional[int] = None
         self._current = -1
@@ -2407,6 +2410,7 @@ def optim(self) -> base.Optimizer:
         if self._optim is None:
             self._optim = self._select_optimizer_cls()(self.parametrization, self.budget, self.num_workers)
             self._optim = self._optim if not isinstance(self._optim, NGOptBase) else self._optim.optim
+            self._optim.archive.delegate_to(self.archive)
             logger.debug("%s selected %s optimizer.", *(x.name for x in (self, self._optim)))
         return self._optim
 
diff --git a/nevergrad/optimization/test_utils.py b/nevergrad/optimization/test_utils.py
index 0c79903a9..bb2d220ec 100644
--- a/nevergrad/optimization/test_utils.py
+++ b/nevergrad/optimization/test_utils.py
@@ -97,12 +97,12 @@ def test_pruning() -> None:
     # pruning
     pruning = utils.Pruning(min_len=1, max_len=3)
     # 0 is best optimistic and average, and 3 is best pessimistic (variance=0)
-    archive = pruning(archive)
+    pruning(archive)
     testing.assert_set_equal([x[0] for x in archive.keys_as_arrays()], [0, 3], err_msg=f"Repetition #{k+1}")
     pickle.dumps(archive)  # should be picklable
     # should not change anything this time
-    archive2 = pruning(archive)
-    testing.assert_set_equal([x[0] for x in archive2.keys_as_arrays()], [0, 3], err_msg=f"Repetition #{k+1}")
+    pruning(archive)
+    testing.assert_set_equal([x[0] for x in archive.keys_as_arrays()], [0, 3], err_msg=f"Repetition #{k+1}")
 
 
 @pytest.mark.parametrize(  # type: ignore
diff --git a/nevergrad/optimization/utils.py b/nevergrad/optimization/utils.py
index 74aab135d..922fd21ca 100644
--- a/nevergrad/optimization/utils.py
+++ b/nevergrad/optimization/utils.py
@@ -173,9 +173,27 @@ class Archive(tp.Generic[Y]):
     """
 
     def __init__(self) -> None:
-        self.bytesdict: tp.Dict[bytes, Y] = {}
+        self._data: tp.Union["Archive[Y]", tp.Dict[bytes, Y]] = {}
+
+    @property
+    def bytesdict(self) -> tp.Dict[bytes, Y]:
+        if not isinstance(self._data, Archive):
+            return self._data
+        else:
+            while self._data.is_delegated:  # unroll
+                self._data = self._data._data
+            return self._data._data  # type: ignore
+
+    def delegate_to(self, archive: "Archive[Y]") -> None:
+        self._data = archive
+
+    @property
+    def is_delegated(self) -> bool:
+        return isinstance(self._data, Archive)
 
     def __setitem__(self, x: tp.ArrayLike, value: Y) -> None:
+        if self.is_delegated:
+            raise RuntimeError("Cannot set from a delegated instance")
         self.bytesdict[_tobytes(x)] = value
 
     def __getitem__(self, x: tp.ArrayLike) -> Y:
@@ -255,13 +273,13 @@ def __init__(self, min_len: int, max_len: int):
         self.max_len = max_len
         self._num_prunings = 0  # for testing it is not called too often
 
-    def __call__(self, archive: Archive[MultiValue]) -> Archive[MultiValue]:
-        if len(archive) < self.max_len:
-            return archive
-        return self._prune(archive)
+    def __call__(self, archive: Archive[MultiValue]) -> None:
+        if len(archive) >= self.max_len:
+            self._prune(archive)
 
-    def _prune(self, archive: Archive[MultiValue]) -> Archive[MultiValue]:
+    def _prune(self, archive: Archive[MultiValue]) -> None:
         self._num_prunings += 1
+        assert not isinstance(archive._data, Archive), "Cannot prune on delegated instance"
         # separate function to ease profiling
         quantiles: tp.Dict[str, float] = {}
         threshold = float(self.min_len + 1) / len(archive)
@@ -270,14 +288,13 @@ def _prune(self, archive: Archive[MultiValue]) -> Archive[MultiValue]:
             quantiles[name] = np.quantile(
                 [v.get_estimation(name) for v in archive.values()], threshold, interpolation="lower"
             )
-        new_archive: Archive[MultiValue] = Archive()
-        new_archive.bytesdict = {
+        bytesdict = {
             b: v
             for b, v in archive.bytesdict.items()
             if any(v.get_estimation(n) < quantiles[n] for n in names)
         }  # strict comparison to make sure we prune even for values repeated maaany times
         # this may remove all points though, but nevermind for now
-        return new_archive
+        archive._data = bytesdict
 
     @classmethod
     def sensible_default(cls, num_workers: int, dimension: int) -> "Pruning":