If you have them set at the Openbuilds defaults (2500 mm/min I believe) you could probably go a bit faster - increase them gradually until you get problems - keep an eye on your leadscrews for whipping. I have a 1010 workbee upgraded with linear rails which I have set the rapids to 4000 mm/min - I can't go any faster until I fit longer leadscrews so I can tension them. Alex. PS you won't notice a lot of difference during a job, as most rapid moves will be fairly short. It is noticeable if you have to re-home from the opposite corner from where your homing switches are.
For files with a lot of short moves (3D carves) the thing that will speed up the cutting most is increasing acceleration rates. Figure out your rapid speeds first, then up your acceleration rates until the machine stalls and then back off about 20% so you have a nice safe margin of error.
