Cheers for the suggestion, but the problem I have is the files in question are only considered temp in hindsight, eg: maybe a bad render that gets re-done a few times. Cases where I'm hoping the result is not temp, but say I notice a problem and have to re-do it, in hindsight that first render now becomes an unnecessary temp file (but a very very large one). Also some apps I use automatically generate backup versions of files, which can be quite large. I need these files to sync, so can't exclude them, but I'd be happy with it happening once a day rather than when I'm working. Disk IO performance is a huge thing for my uses, I can't have a utility crawling the drive when I'm trying to read off it at maximum speed etc. My short term solution is to just pause btsync and then enable it when I'm done - not really the best solution but kinda works for now.