What is a simple fast and easy way to improve processing power?

You can't just increase your processing power. Raw processing impetus is dependent on the hardware that you own.

You can watch your "processing power" by using benchmarks. Benchmarks are standardized tests where the results can be compared to other CPUs. This can Be through with benchmarking your computer yourself, or looking up the benchmark results of your HARDWARE.

"How much" processing power you need to run a process is dependent on the manner of application being used. For example, surfing the net does not require much 'processing power'. However, coding a video or playing a video game are more CPU intensive.

You indicate that your your computer has been moving slowly. As stated earlier, you cannot just 'simply' make your computer go faster. However, you can make your computer feel more 'responsive'. This can include clearing/cleaning out your startup processes (if your interested, you can look up 'msconfig', but i only recommend using it provided you know what you're doing), or simply starting fresh by completely reinstalling your operating system.

You can also make your computer 'feel faster' with a fairly inexpensive Memory/RAM upgrade. If you are more daring, then a CPU upgrade will increase your processing ability, but is not recommended unless the upgrade is cost effective and compatible with your personal.

(And let me stress, compatible. Most new processors/graphics cards/ or any part for that entity, are not compatible with older personal. There is none point in upgrading to 'old' hardware because of price (low supply) and the minimal performance increase. It's like upgrading from a serried car to other compact car, hostile upgrading from a compact car to a Ferrari - within jargon of performance)