If your laptop supports the Intel® Extreme Tuning Utility (Intel® XTU) then use that to control your CPU.
Some laptops have decided to disable the Intel Turbo Boost feature whenever the GPU is active. The default speed for a Core i7-3740QM is 2700 MHz so when loaded, your laptop should definitely not be running slower than that. Run a single thread of the TS Bench or any simple benchmark like Super Pi Mod to test this.
If you use ThrottleStop or XTU to enable Turbo Boost, the maximum amount of Turbo Boost you get can be limited by how many cores are active, power consumption or the amount of current flowing through your CPU. The Turbo Boost current limit is usually set high enough in the bios so that is rarely a factor.
Here are the default maximum speeds you can achieve based on how many cores are in the active state:
4 core: 3500 MHz
3 core: 3600 MHz
2 core: 3700 MHz
1 core: 3700 MHz
As more cores become actively working, the maximum speed your CPU will run at will decrease. When cores go into the C3 / C6 sleep state and become inactive, the remaining active cores can increase in speed.
Those are the maximums. You can also be limited by power consumption. Usually for the first 28 seconds your CPU can Turbo Boost up to its highest speed. Once this time limit runs out, the maximum power consumption of the CPU is forced to decrease. The CPU will decrease the Turbo Boost multiplier to accomplish this.
Some laptops let you increase the Turbo Power power and time limits and some laptops lock this feature in the bios so these limits can not be increased when in Windows. Have a look in the ThrottleStop TPL window to see if these values can be adjusted. Intel XTU should show you the same thing.
Your CPU also supports some limited overclocking. The above maximum Turbo values can usually be increased by 4 bins each so your maximum overclocked limits will look like this:
4 core: 3900 MHz
3 core: 4000 MHz
2 core: 4100 MHz
1 core: 4100 MHz
This feature might not be available or it might be locked by the bios.
This is a mobile CPU so when idle it is designed to enter the low power sleep states like C3 / C6. That's not a bad thing. It saves power and your laptop will run cooler without any noticeable difference in performance. On a non-Extreme CPU like you have, at least C3 has to be available for Intel Turbo Boost to function correctly.
If XTU doesn't work on your board, try adjusting your Turbo multipliers to 39, 40, 41, 41 in ThrottleStop. You might have to go into Sleep mode and then Resume before these values are available or it might not work at all. Also adjust the Set Multiplier value after you adjust the TRL values.
If you want to help with ThrottleStop development, can you run the MSR Finder program and take a snapshot of your CPU registers? You can copy and paste the results and send me a PM with the info. Thanks.