Despite the column "FGC", it is not really a full GC. What the CMS is doing is a concurrent collection to see if anything can be cleaned up from the old collection (which you can see it is doing). The way to can tell this not a full GC, is that a full GC clears the eden space and copies from one survivor space to another.
IMHO The more options you use, the more likely you will come across some combination with surprising results. I would stick to the minimum of options and see how that performs. Only add option when you know they will always help.
Try to start with,
-mx4g -XX:MaxPermSize=128m -XX:+UseConcMarkSweepGC