How to Optimize CPU for Gaming?

You can't update a CPU nor RAM, motherboard or SSD. You choose the right ones.
You don't mention the graphic card you have. That's important also.

Nice to have SSD but for today's games you need a capable GPU (graphic card.)

Many i5 CPUs have graphics but no gamer I know will like that.

Unless all you play is DOOM?

To optimize your CPU for gaming, you can follow several steps to ensure the best performance. Here are some recommendations:
Update drivers: Install the latest CPU drivers for performance improvements and bug fixes.

Adjust power settings: Select the High-Performance power plan to ensure maximum CPU performance.

Disable unnecessary processes: Close background applications to free up system resources.

Overclocking (if supported): Increase CPU clock speed cautiously for extra performance (research and cooling required).

Manage system resources: Identify and close resource-intensive processes using task manager or system monitoring tools.

Keep system cool: Clean dust, use cooling pads, and ensure proper airflow to prevent overheating.

Consider hardware upgrades: Upgrade to a more powerful CPU if necessary for better gaming performance.

Remember, a well-rounded system with optimized components like the graphics card, RAM, and storage is important for an optimal gaming experience.

Certainly, here's a shorter version:

Good on you for the system upgrade! If you're still facing game lag, try these:

Check your graphics card.
Consider more RAM (16GB).
Keep drivers updated.
Close background apps.
Adjust in-game settings.
Confirm monitor settings.
Watch your system's temperature.
Look for game updates.
Ensure a stable internet connection.
These tweaks should boost your gaming experience. Ask for specifics if needed!

Upgrading from a P4 to an Intel Core i5 11th Gen and adding an SSD was a significant performance boost, but for optimal gaming, ensure you have ample RAM (8GB or more), a dedicated graphics card for modern games, up-to-date drivers, and proper cooling to prevent overheating. Close unnecessary background applications, adjust in-game settings to match your hardware, and verify that your SSD has sufficient free space. Consider a high-speed internet connection for online gaming and always meet or exceed a game's minimum system requirements. If issues persist, upgrading your graphics card or adding more RAM might be the next steps to consider.