yeah GCD and combat lag has gotten worse since last patch. There are other threads blaming it on the collections system etc. I wish they would fix it my dps parses have been taking big hits.
As a marauder, I've noticed 3 forms of this lag (while having 100ms latency or less)-
Carnage- skill activates, consumes GCD without actually doing anything resulting in a 3 sec GCD.
Annihilation- classic server lag feeling where skills stick and don't activate immediately, results in at leqst a 2 sec gcd.
Both specs-stutter lag where a GCD begins, then as the next skill is queued, the GCD resets, resulting in ~2 sec GCD.
These problems seem to be way worse with combat logging running, implying there's a problem woth combat logging and server. I haven't been able to parse on the dummy in any meaningful way the past week or two as these screw ups are totally random.