The logs would seem to indicate a topology change in the cluster (either a rebalance or failover) – (specifically, it’s stating all the vBuckets have changed and the order of the servers have changed as well):
245732992ms [I0] {22131} [INFO] (newconfig - L:107) Config Diff: [ vBuckets Modified=1024 ], [Sequence Changed=1]
245732992ms [I0] {22131} [INFO] (newconfig - L:206) Reusing server 10.99.24.24:11210 (0x23e3e70). OldIndex=0. NewIndex=1
245732992ms [I0] {22131} [INFO] (newconfig - L:206) Reusing server 10.99.24.25:11210 (0x23fab70). OldIndex=1. NewIndex=0
While this condition in itself should not cause operations to time out, rebalance operations to put some extra load on the server, especially in older versions.
While it is highly recommended to use the couchbase:// scheme (rather than the http:// scheme) for all cluster versions, bootstrapping/configuring via the memcached protocol (port 11210) is only available from Couchbase version 2.5 and higher. Since you are on 2.2 only the HTTP configuration is available.
Finally, it would indicate that either the network or the cluster is under some load by additionally examining the total time to retrieve the cluster configuration (several milliseconds). While this is within the margin of normal operations, typically configurations are received in a smaller timeframe.