You can try lower the voltage for your processor in the BIOS settings. This will limit the resources a bit. You can create a simple c++ program that is filling all the memmory and using 100 % of cpu time.
this is for CPU usage:
#include <stdio.h>
#include <time.h>
#include <omp.h>
int main() {
double start, end;
double runTime;
start = omp_get_wtime();
int num = 1,primes = 0;
int limit = 1000000;
#pragma omp parallel for schedule(dynamic) reduction(+ : primes)
for (num = 1; num <= limit; num++) {
int i = 2;
while(i <= num) {
if(num % i == 0)
break;
i++;
}
if(i == num)
primes++;
// printf("%d prime numbers calculated\n",primes);
}
end = omp_get_wtime();
runTime = end - start;
printf("This machine calculated all %d prime numbers under %d in %g seconds\n",primes,limit,runTime);
return 0;
}
About the memory - setup the Oracle Virtual Host. Install some system as the virtual machine and give it lots of memory to use. Of fire couple of virtual machines. this is the easiest non programming way i can think of.
For flash games slowdown in particular you can use : http://www.cheatengine.org/downloads.php
I found the video with the guide how to use cheatengine: http://www.youtube.com/watch?v=2W6L1iqGUR0