Going off [1] it looks like TokuMX is a similar multiple faster than Mongo than Postgre is from Mongo, so I'd guess Postgre and Toku would be fairly similar speed wise. Obviously depending on your data and search patterns one may still be significantly faster than the other as the usual caveat.

[1] http://www.databasejournal.com/sqletc/tokumx-compared-to-mon...