Expensive operations running on initialization of tabs

[fedejeanne]

Some tabs still rely on the method initializeFrom to perform the heavy lifting.

This sometimes leads to unnecessary (sometimes even expensive) calculations, since not all tabs are ever going to be activated (i.e. selected).

These are the ones I've identified so far:

• TestTab (belongs to Plugin Test configuration) --> Not possible, see comment
• PluginsTab (in the Plugin and Plugin Test configurations) --> Move long running operations to the activation of the PluginsTab #1233

[fedejeanne]

BTW these are some samplings showing the initialization times of TestTab and PluginsTab (see vi-eclipse/Eclipse-PDE#2)

Snapshot (same as eclipse-jdt/eclipse.jdt.core#1214): open-run-configurations-dialog.zip

[fedejeanne]

Improving the TestTab will not be possible (or at least now worth the effort) because the expensive operation is calculating the methods that can run in a test configuration. This is necessary to calculate if the configuration is valid (isValid) and this is necessary when initializing the tab because the whole configuration is only valid if each one of their tabs is valid.

This wasn't the case with the PluginsTab because the validation in that tab was a NO-OP.

I'm scratching the task from this issue (in the description)