Basically, parsing the percentages, using compressed data in RAM is ~1 order of magnitude slower to get into memory, and less than 1 order of magnitude slower to read from RAM. That is still around 2 (or more depending on setup) orders of magnitude faster than the hit to go to SSD / SSD RAID.
To guy below me: Ah, thanks. I thought the guy above was trying to say it's slower than paging to disk. : )