So, the problem will be with the graphics CPU (or whatever they call them). When you start a game it will run with selected graphics card. Mostly the Emergency 4 will run with Intel graphics which are bad in my opinion. To fix this you will need to do following steps:
1) Open the Emergency 4 game files directory.
I use steam version of the game, so for me it will go like this: This Computer > Local Disk (C:) > Program Files (x86) > Steam > steamapps > common > Emergency 4 DELUXE
2) After you find the file direcotry for Emergency 4, you will need to find em4.exe (I don't know the what .exe will be for 991 First Responders, if you know comment down below).
3) Select the em4.exe and the right click on it. After that find option called "Run with Graphics processor". Extend the option and then click on "Change default graphics processor"
4) Wait until the window appears and wait until it loads.
5) Now, you will need to go to option called "1. Select program to be customized". Check if it has below it Emergency 4 (em4.exe) selected.
6) Move to the option 2, here you will need to select "Processor Nvidia with high performance". Skip the option 3.
7) Go back to option 1 and then click "add". After that you will have to save those settings.
Note: This solution is for Nvidia graphics CPU.
I hope it helped you all.