diff --git a/website/server/models/challenge.js b/website/server/models/challenge.js
index 4fddabac2c..511c969429 100644
--- a/website/server/models/challenge.js
+++ b/website/server/models/challenge.js
@@ -191,7 +191,7 @@ schema.methods.addTasks = async function challengeAddTasks (tasks) {
   let challenge = this;
   let membersIds = await _fetchMembersIds(challenge._id);
 
-  let queue = new cwait.TaskQueue(Bluebird, 5); // process only 5 users concurrently
+  let queue = new cwait.TaskQueue(Bluebird, 25); // process only 5 users concurrently
 
   await Bluebird.map(membersIds, queue.wrap((memberId) => {
     return _addTaskFn(challenge, tasks, memberId);