How to avoid that an installed package is reinstalled every time an used runtime package is recompiled?

I have a designtime package which is installed in the IDE and uses classes and functions defined in a runtime package.

Each time I compile or build the runtime package, it seems that the designtime package is automatically reinstalled.

This operation starts after pressing the "Ok" button of the "Compiling window" and takes a several seconds.

Is there a way to avoid this?

You cannot avoid that. The designtime package depends on the runtime package. When you recompile the runtime package it has to be unloaded and reloaded to make the new compilation effective. Unloading the runtime package requires all dependent packages to be unloaded before. At least the IDE is clever enough to automatically reload the dependent packages after loading the new runtime package.