The m93 tiny is available with up to an Intel Core i7-4765T which score around a 7200 on the benchmarks..the i5 4570T scores about a 4900...
There is no exact science to this, as the benchmarks dont tell the whole story and cameras vary....but just as an example, im running 12mp using direct to disk on a i5-3470 which benchmarks in between the two (6166) using direct to disk im at about 30 percent when its not recording...
Same system with 3 dahuas 1.3mp each and a vga camera...NOT using direct to disc on this one and i use about 19%...would be lower with direct to disk...
I7-4770 with 8 cameras 22mp total, direct to disc ..using about 22% at idle..
So with the i5 you could do about 16-18mp and keep it about 50-60 percent..thats a real rough estimate...