I recently upgraded the hard drive in a late-2011 macbook pro to a Samsung 840 Pro SSD. Raw benchmarks were quite fast, but the overall feel of the system became very laggy. I noticed that boot was very fast and the first 60 seconds or so were extremely responsive. Unfortunately, after a minute or so, the system became very slow. Commands which normally take a few thousandths of a second to complete began to take .1 to .3 seconds.
I narrowed it down to the OAS: whenever it was disabled, the system responded as expected. When it is enabled (which it would do automatically after a few minutes) the latency returned.
One thing I noticed about the latency is that it always seems to come in 100ms increments. A command which normally took around .017 +- .002 seconds to complete (time sha1sum /usr/bin/git) would take either .117, .217, .317, etc.
I did not notice any issues before the SSD upgrade. The install was performed by a time machine restore onto the new disk, then TRIM was enabled through Trim Enabler.
I appear to be running McAfee security 1.1.0 (1309), Anti-malware version 9.1.0 (4478).
Any ideas what could be causing OAS to slow things down so much?