(I've never developed an Eclipse plugin, I've just looked at it from a high level. Mainly tracking down issues with various plugins).
I'm not sure what kind of plugin you created, but have you dealt with creating an editor for a language? The issues I've seen is that to populate various views you have to use an event system. When you start having to work with a lot of different views and populating it with various data it starts to open up holes where things can start to slow down. Then depending on the type of events you throw, other plugins have react to them and cause certain operations (like a save or recompile) to slow things down a bit.
I'm not sure what kind of plugin you created, but have you dealt with creating an editor for a language? The issues I've seen is that to populate various views you have to use an event system. When you start having to work with a lot of different views and populating it with various data it starts to open up holes where things can start to slow down. Then depending on the type of events you throw, other plugins have react to them and cause certain operations (like a save or recompile) to slow things down a bit.