Here's where I come in: I've tried to do the exact same thing. I've isolated my problem, but it may not be the same as yours. My problem lies within date.cs in my BTTF mod. With date.cs in the CLEO folder, my SA experiences an extreme lag. However, if date.cs is removed from the CLEO folder, there is no lag. If date.cs is split up in any fashion, the game crashes. I've made 2 GTA Forums topics about this and none have provided me with an alternative (except dual booting Windows 7). Here are the GTAForums topics I made, just for reference, although they will probably be of no help. http://gtaforums.com/topic/815905-sa-windows-1081-lag/ http://gtaforums.com/topic/822152-sa-windows-10-cleo-script-lag/ Its weird that my NFS MW mod works just fine with the same types of opcodes in the init script (audiostream). I just run the exe in Win 7 Compatibility mode. I have not tried the newest CLEO 4, since I've read that it has bugs and has been neglected over the past 6 months. Sorry about this inconclusive response. I thought it would be informative to post my findings so far.