It seems that with the new version, whenever you have a complex glyph the application becomes extremely non-responsive. This didn’t occur with the initial release of v6 but the new releases make creating complex glyphs almost impossible.
I ran a test on a moderately complex glyph with 89 contours and 1271 points, comparing the performance in FontCreator 5.6 and FontCreator 6.1 build 216. In both cases, real-time validation was on, and in Tools, Options, Validation, Global detection was enabled.
Double-clicking on the glyph in the overview window took about 8 seconds to open in FontCreator 6.1 while in version 5.6 it took about 1 second.
Scrolling left and right between complex glyphs in the glyph edit window is another good way to test this. Ctrl A to select all in the glyph edit window also shows a signficant delay in FontCreator 6.1
There is clearly a signficant problem here for anyone editing complex glyphs.
Right now we can’t improve the performance, so I suggest you turn of validation features for complex glyphs. You can made such changes in the Options window → Validation.
Thanks for looking into this problem. I hope this can be fixed in the next release. Validation is a very important feature and changing the parameters of validation each time is not very efficient when working on a complex font.
Thought I should let you know that the performance around complex glyphs has greatly improved with this latest release! 
I agree.
I don’t recall we did something to improve this… Anyway we’re glad to know you enjoy the latest release.