The reason for the speed stepping is to prevent damage to the CPU. It only lowers the clock speed if the CPU is approaching dangerous temperature levels.
If you disable speed stepping the CPU can be damage from the heat.
Since this is a laptop, you are limited on how to bring the temperature down. What kind of surface are you using the laptop on? Make sure that you are not using a surface that restrics the fan vent and completely covers it. (Like sheets on a bed)
You can buy a laptop cooler that has a built it fan which will help bring the temperature in the laptop down.