Best way to increase keyframes duration

I am working on a project that has “a lot” (for me at least :slight_smile: ) of key frames. I did not pay really attention to the timing of the animation, and now I would like to increase the length of a specific keyframe.
Unfortunately, Synfig crashes when I try to modify such a parameter.
I realize that it was getting better when the following keyframes were unchecked, but I cannot select multiple KF at a time, so I was wondering if there where a better solution ?
Thanks for your help !

It crashes or it freezes for a while?

I never waited more than 6-7 min, so I guess freeze is a better description !

Have you tried selecting that desired keyframe and pushing it while pressing holding Alt key? This way multiple keyframes before/after depending on your dragging left/right will be affected too. There’s no way to select multiple keyframes using mouse click.

Unfortunately, I don’t know how to do that :S --> can I do that from the keyframes panel ?

I can select and move multiple waypoints in the graph editor, but I need to repeat that for all the parameters I guess, so it is quite long also !

On the top of timetrack panel :slight_smile: