EDITED: On windows 10 with 2.5 GHZ max while running an app, I locked my system and closed the lid right after, noticed the percentage of the CPU usage increased for the task and then goes back to normal(a few minutes after I have signed back in) in Task manager. Is there a way to have the CPU be at 100% or 90% usage in Taskmanager by increasing its clock speed so the app can as well run faster?
What's likely happening is the result of a feature called SpeedStep. There should be an option in the BIOS to enable/disable it (it may be listed under EIST).
If you're simply disabling it so that your app runs faster, you're probably going to be wasting CPU cycles and power. The CPU is smart enough to know when the app needs more resources and will increase it's frequency up to the advertised spec until it's no longer needed - then step back down to a lower idle frequency to minimise power draw and heat generation.