i suggest to make a “GLOBAL Timeline Curve” to control the whole animation(or each individual object 's) timeline(animation speed) by an editable curve . in all synfig version, the curve View( Graphs) seem not editable.
And the “Global timeline Curve” will have a few Bulit-in curve type such as sine ,cos,ping pong…etc
can the performance be improved by the help of OpenGl(hardware acceleration) ?? it seem that whatever the display card is ,no performance change…
=preview and render=
i think it is great if the “end frame” field can be a drop down list that provide a few option such as “whole timeline”,“last keyframe” and “custom”.