The shutter lag on my Fujifilm FinePix S1800 is much longer in EVF mode (just under half a second) than in LCD mode (about 0.15 seconds). What would explain this anomaly?
As has been addressed in a comment to your question, it could do with the amount of memory the camera has, and how much processing it needs to do. If all other parameters are equal (settings, subject, exposure), then I have no idea. The EVF has less pixels than the LCD, so it should process quicker, which isn't your case.
The only other thing I can suggest, is asking whether you're encounter actual shutter lag, or just EVF refresh rate lag?