Usual culprit for laptops is the monster reader/item reader plugins. Laptops CPUs are clocked lower than their desktop counterparts, and generally have lower instructions per clock as well. The older versions of these addons have an update rate fast enough to cause very noticable slowdowns in...
By chance are you using the monster or item reader lua plugins? CPUs with weaker single core will struggle with them on. If this is the case, disable monster reader/set the item reader to a slower update rate (~1-2 seconds).