This one has been annoying me for a long time and having switched directly from D2007 to XE2 a few months back I can't vouch for when this may have started, but on D2007 I didn't have the issue.
The larger a unit grows, the slower it becomes to use F12 to switch between unit and form when code changes have been made. Even if you undock the form designer (back to D7 format), just clicking back into the form when code has been changed causes the BDS.exe to max out on CPU for a long time. In my case, on my largest form (30,000 lines) this can be over a minute. I'm not sure what checking is going on when reactivating the form, but if the IDE has been "told" that all is uptodate, then the switch is instantaneuos. My workaround is therefore to Ctrl+F9 to compile the form before reactivating the form. The time taken to compile is only a few seconds. I can then switch instantly to the form without issue. Compare that to the minute or more wait I endure if I don't compile before switching...
So, what are the possibilities, apart from reducing the unit size ?!
