I'm surprised how many are suggesting two SSDs. I run 5 on my machine with the cheapo RiData 32GB MLC version and everything is smooth. The ONLY time there is a bit of lag is when WG is coming to the very end and everything is going nuts... that could definitely be lag other than my harddrive (note: it's still very playable, but there can be a couple seconds of small stuttering).

Peeps are going overboard with the expensive SSDs, RAID configs, etc.