Latitude e6430 low cpu speeds after waking up from sleep

Whenever my e6430 wakes up from sleep, it locks the maximum speed to 2.4ghz, usually i runs at 3.1-3.3 whenever i'm doing something intensive. Restarting the laptop fixes it and allows it to reach the 3.1-3.3 cpu speeds but it's not really a convenient solution.

Any ideas? Thanks.