diff --git a/src/models/Site.js b/src/models/Site.js
index f9cfb8e0..dfd84efb 100755
--- a/src/models/Site.js
+++ b/src/models/Site.js
@@ -912,12 +912,10 @@ Wil je dit liever niet? Dan hoef je alleen een keer in te loggen op de website o
   }
 
   Site.prototype.willAnonymizeAllUsers = async function () {
-
     let self = this;
     let result = {};
 
     try {
-
       if (!self.id) throw Error('Site not found');
       if (!self.config.project.projectHasEnded) throw Error('Cannot anonymize users on an active site - first set the project-has-ended parameter');
 
@@ -929,43 +927,46 @@ Wil je dit liever niet? Dan hoef je alleen een keer in te loggen op de website o
 
       // extract externalUserIds
       result.externalUserIds = result.users.filter( user => user.externalUserId ).map( user => user.externalUserId );
-
     } catch (err) {
       console.log(err);
       throw err;
     }
 
     return result;
-    
   }
 
-  Site.prototype.doAnonymizeAllUsers = async function () {
-
+  Site.prototype.doAnonymizeAllUsers = async function (usersToAnonymize, externalUserIds, useOauth='default') {
     // anonymize all users for this site
     let self = this;
-    let result;
-
+    const amountOfUsersPerSecond = 50;
     try {
-
-      result = await self.willAnonymizeAllUsers();
-
-      let users = [ ...result.users ]
-
-      // anonymize users
-      for (const user of users) {
-        user.site = self;
-        let res = await user.doAnonymize();
-        user.site = null;
+      // Anonymize users
+      for (const user of usersToAnonymize) {
+        await new Promise((resolve, reject) => {
+          setTimeout(async function() {
+            user.site = self;
+            let res = await user.doAnonymize();
+            user.site = null;
+          }, 1000 / amountOfUsersPerSecond)
+        })       
+        .then(result => resolve() )
+          .catch(function (err) {
+            throw err;
+          });
       }
 
+      for (let externalUserId of externalUserIds) {
+        let users = await db.User.findAll({ where: { externalUserId } });
+        if (users.length == 0) {
+          // no api users left for this oauth user, so remove the oauth user
+          let siteConfig = self && merge({}, self.config, { id: self.id });
+            await OAuthApi.deleteUser({ siteConfig, useOauth, userData: { id: externalUserId }})
+        }
+      }
     } catch (err) {
       console.log(err);
       throw err;
     }
-
-    result.message = 'Ok';
-    return result;
-
   }
 
   Site.prototype.isVoteActive = function () {
diff --git a/src/routes/api/site.js b/src/routes/api/site.js
index 77f1d19e..9761ed1b 100755
--- a/src/routes/api/site.js
+++ b/src/routes/api/site.js
@@ -282,40 +282,25 @@ router.route('/:siteId(\\d+)/:willOrDo(will|do)-anonymize-all-users')
 				if ( !found ) throw new Error('Site not found');
 				req.results = found;
 				req.site = req.results; // middleware expects this to exist
-        next();
-				return null;
+        		next();
 			})
 			.catch(next);
 	})
   .put(async function (req, res, next) {
     try {
+		const result = await req.site.willAnonymizeAllUsers();
+		req.results = result;
       if (req.params.willOrDo == 'do') {
-        req.results = await req.site.doAnonymizeAllUsers();
-      } else {
-        req.results = await req.site.willAnonymizeAllUsers();
-      }
-      next();
-			return null;
-    } catch (err) {
-      return next(err);
-    }
-  })
-  .put(async function (req, res, next) {
-    try {
-      if (req.results.externalUserIds.length == 0) return next();
-      for (let externalUserId of req.results.externalUserIds) {
-        let users = await db.User.findAll({ where: { externalUserId } });
-        if (users.length == 0) {
-          // no api users left for this oauth user, so remove the oauth user
-          let which = req.query.useOauth || 'default';
-          let siteConfig = req.site && merge({}, req.site.config, { id: req.site.id });
-          if (req.params.willOrDo == 'do') {
-            let result = await OAuthApi.deleteUser({ siteConfig, which, userData: { id: externalUserId }})
-          }
-        }
-      }
+		result.message = 'Ok';
+
+		req.site.doAnonymizeAllUsers(
+			[...result.users], 
+			[...result.externalUserIds],
+			req.query.useOauth
+
+		);
+      } 
       next();
-			return null;
     } catch (err) {
       return next(err);
     }