Just disable 'backup at regular intervals' in the Export Particles settings.
It's enabled so that if you're exporting a huge cache, if it crashes or fails at any point, the particles exported up to the point of the last mesh file backup will still be usable.
But if you've got a setup with really heavy meshes that is not at risk of failing, then it'll being doing a lot of work for no reason.
I think I planned to have it off by default at some point...but if it's off by default then it won't be on when you need it most (unplanned export crash). Although I haven't had too many reports of that happening...so maybe it's worth having it off again.
It's enabled so that if you're exporting a huge cache, if it crashes or fails at any point, the particles exported up to the point of the last mesh file backup will still be usable.
But if you've got a setup with really heavy meshes that is not at risk of failing, then it'll being doing a lot of work for no reason.
I think I planned to have it off by default at some point...but if it's off by default then it won't be on when you need it most (unplanned export crash). Although I haven't had too many reports of that happening...so maybe it's worth having it off again.