When I edit a font using FontCreator, the exported font file has a much lower size than the original one. Is this normal?
Like any font editor, FontCreator tries to reconstruct the OpenType font into an internal format. During this conversion some data might get lost, but FontCreator is in most cases the best editor, especially concerning OpenType layout features.
FontCreator uses advanced compression algorithms, which usually result in smaller file sizes.
Thank you very much for your answer. For example, a Garamond Pro-Regular.ttf by Softmaker (323Kb), after correcting some kerning problems with FontCreator, was changed to 114Kb. And so on…
It is hard to tell from here what the exact reason is for this significant size reduction. Do send us the font files and we will make a more detailed comparison.
I have sent the files. I hope they will be useful.
Well, actually most of the savings is due to a severe issue in FontCreator. For some reason it removes hinting data on export. 
Thank you for bringing this to our attention. We will have this fixed ASAP.
Thank you very much for your assistance. I’ll wait for the update that fixes the problem.
We have just released an update that should solve this problem.
It’s impossible for me to test now. I’ll report this evening.
Big difference! Now the exported font has nearly the same size as the original size of the font. Congratulations! Once more, quick update to solve a problem!