diff --git a/src/amplitude_experiment/cohort/cohort_loader.py b/src/amplitude_experiment/cohort/cohort_loader.py
index e5d6639..14f639e 100644
--- a/src/amplitude_experiment/cohort/cohort_loader.py
+++ b/src/amplitude_experiment/cohort/cohort_loader.py
@@ -6,7 +6,7 @@
 from .cohort import Cohort
 from .cohort_download_api import CohortDownloadApi
 from .cohort_storage import CohortStorage
-from ..exception import CohortUpdateException
+from ..exception import CohortsDownloadException
 
 
 class CohortLoader:
@@ -30,39 +30,37 @@ def load_cohort(self, cohort_id: str) -> Future:
 
     def _remove_job(self, cohort_id: str):
         if cohort_id in self.jobs:
-            del self.jobs[cohort_id]
+            with self.lock_jobs:
+                self.jobs.pop(cohort_id, None)
 
     def download_cohort(self, cohort_id: str) -> Cohort:
         cohort = self.cohort_storage.get_cohort(cohort_id)
         return self.cohort_download_api.get_cohort(cohort_id, cohort)
 
-    def update_stored_cohorts(self) -> Future:
-        def update_task():
+    def download_cohorts(self, cohort_ids: Set[str]) -> Future:
+        def update_task(task_cohort_ids):
             errors = []
-            cohort_ids = self.cohort_storage.get_cohort_ids()
-
             futures = []
-            with self.lock_jobs:
-                for cohort_id in cohort_ids:
-                    future = self.load_cohort(cohort_id)
-                    futures.append(future)
+            for cohort_id in task_cohort_ids:
+                future = self.load_cohort(cohort_id)
+                futures.append(future)
 
             for future in as_completed(futures):
-                cohort_id = next(c_id for c_id, f in self.jobs.items() if f == future)
                 try:
                     future.result()
                 except Exception as e:
-                    errors.append((cohort_id, e))
+                    cohort_id = next((c_id for c_id, f in self.jobs.items() if f == future), None)
+                    if cohort_id:
+                        errors.append((cohort_id, e))
 
             if errors:
-                raise CohortUpdateException(errors)
+                raise CohortsDownloadException(errors)
 
-        return self.executor.submit(update_task)
+        return self.executor.submit(update_task, cohort_ids)
 
     def __load_cohort_internal(self, cohort_id):
         try:
             cohort = self.download_cohort(cohort_id)
-            # None is returned when cohort is not modified
             if cohort is not None:
                 self.cohort_storage.put_cohort(cohort)
         except Exception as e:
diff --git a/src/amplitude_experiment/deployment/deployment_runner.py b/src/amplitude_experiment/deployment/deployment_runner.py
index e826aed..f61b657 100644
--- a/src/amplitude_experiment/deployment/deployment_runner.py
+++ b/src/amplitude_experiment/deployment/deployment_runner.py
@@ -8,7 +8,9 @@
 from ..flag.flag_config_api import FlagConfigApi
 from ..flag.flag_config_storage import FlagConfigStorage
 from ..local.poller import Poller
-from ..util.flag_config import get_all_cohort_ids_from_flag
+from ..util.flag_config import get_all_cohort_ids_from_flag, get_all_cohort_ids_from_flags
+
+COHORT_POLLING_INTERVAL_MILLIS = 60000
 
 
 class DeploymentRunner:
@@ -29,7 +31,7 @@ def __init__(
         self.lock = threading.Lock()
         self.flag_poller = Poller(self.config.flag_config_polling_interval_millis / 1000, self.__periodic_flag_update)
         if self.cohort_loader:
-            self.cohort_poller = Poller(self.config.flag_config_polling_interval_millis / 1000,
+            self.cohort_poller = Poller(COHORT_POLLING_INTERVAL_MILLIS / 1000,
                                         self.__update_cohorts)
         self.logger = logger
 
@@ -71,15 +73,12 @@ def __update_flag_configs(self):
 
         existing_cohort_ids = self.cohort_storage.get_cohort_ids()
         cohort_ids_to_download = new_cohort_ids - existing_cohort_ids
-        cohort_download_errors = []
 
         # download all new cohorts
-        for cohort_id in cohort_ids_to_download:
-            try:
-                self.cohort_loader.load_cohort(cohort_id).result()
-            except Exception as e:
-                cohort_download_errors.append((cohort_id, str(e)))
-                self.logger.warning(f"Download cohort {cohort_id} failed: {e}")
+        try:
+            self.cohort_loader.download_cohorts(cohort_ids_to_download).result()
+        except Exception as e:
+            self.logger.warning(f"Error while downloading cohorts: {e}")
 
         # get updated set of cohort ids
         updated_cohort_ids = self.cohort_storage.get_cohort_ids()
@@ -97,8 +96,9 @@ def __update_flag_configs(self):
         self.logger.debug(f"Refreshed {len(flag_configs)} flag configs.")
 
     def __update_cohorts(self):
+        cohort_ids = get_all_cohort_ids_from_flags(list(self.flag_config_storage.get_flag_configs().values()))
         try:
-            self.cohort_loader.update_stored_cohorts().result()
+            self.cohort_loader.download_cohorts(cohort_ids).result()
         except Exception as e:
             self.logger.warning(f"Error while updating cohorts: {e}")
 
diff --git a/src/amplitude_experiment/exception.py b/src/amplitude_experiment/exception.py
index 7281a0e..92ed0e9 100644
--- a/src/amplitude_experiment/exception.py
+++ b/src/amplitude_experiment/exception.py
@@ -15,7 +15,7 @@ def __init__(self, status_code, message):
         self.status_code = status_code
 
 
-class CohortUpdateException(Exception):
+class CohortsDownloadException(Exception):
     def __init__(self, errors):
         self.errors = errors
         super().__init__(self.__str__())