Hi! When you restored, did you do a "setup as new" or a "restore from backup"? Because the second might cause issues since you were jailbroken before.
Try performing two hard resets first (reboot the phone by holding down the home/power buttons simultaneously). If it doesnt fix it, you might need to restore.
Another solution i know to fix the lag (which usually has to do with winterboard) Is to install Barrel.