These changes cannot be done in Laravel Forge. You will have to go to your AWS console.

Speed can be increased by changing CPU and memory of your server.

CPU refers to the number of CPUs and memory refers to the RAM. You can increase both by change the instance type of your AWS server.

For example, a t2.nano have 1 CPU and 0.5 GB of RAM memory. If you want to increase the speed of your application on your server, you can upgrade it to t2.medium which has 2 CPUs and 4 GB of memory.

Check on this forum to increase speed of your server