Well I did my system drive last night, and here are the results. I started off by running a test of all encryption methods in TC to look at theoretical speeds, and picked Twofish encryption. The benchmark put it at a mean speed of 54 MB/s, which is right at the max speed for my HD.
As far as installation goes, it couldn't be easier. The bootloader works perfectly, and it forces you to create a rescue CD in case the HD is damaged. Total time to encrypt my 250 GB HD was around 3 hours, with no overwriting.
Once everything was encrypted though, the benchmarks were a little disappointing.
Hard Drive: Western Digital 250 GB SATA 150 (WD2500YD)
Before:
Average Transfer: 46.5 MB/s
Access Time: 13.9 ms
CPU Usage: 4.3%
After:
Average Transfer: 36.2 MB/s
Access Time: 13.7 ms
CPU Usage: 38%
One thing that I can't show is the transfer speed over time. On the normal drive it decreases over time in a fairly linear fashion, but for the encrypted drive it stays more or less constant. So for the normal HD the transfer speed for small files is around 56 MB/s.
In all, I haven't noticed any dramatic changes in the performance of windows. I'm afraid to load up Crysis though
