mobile

I have flashed all the factory images of android 5.1 on my nexus 6. The same thing keeps happening and that is when i touch the google search bar on the google launcher it pulls down my search history really choppy and laggy. My entire device is not as smooth as it once was. I ran into the "missing system.img" issue when using the flash-all command so i manually flashed each .img file. Has anyone noticed this issue or know what might be causing it?