is it lagging with the proxies enabled? if your cpu supports it, see if h.264 acceleration is turned on in preferences. any intraframe proxies should work well. the smaller the resolution, the less cpu overhead. also, you can disable high quality playback, right click on the program monitor. also, lower the playback resolution. cineform, dnx, prores proxies, should work well.
if you are low on hard drive space, you can create a custom h.264 with very low resolution and in advanced preset, enable “1” every keyframe(disables Delta interframes) at 1 mbps. This will make your proxies 400x smaller than normal.
I believe cineform has the lowest cpu overhead, then dnx, then prores. mxf is also really fast.