Same as with previous release, 32 bit version performs faster in some algos (x16/x17 etc) ...
Have just tested 32vs64 bit on 1080ti's - no difference noticed, niether between 1.19 and 1.20. T-rex miner on the other hand now at least 15% faster in x16r, but way slower in lyra2z.
What is your hashrate per 1080ti with z-enemy 1.20 and with t-rex 0.6.5? And for how long you have conducted the test?