You could overclock the CPU, but that wouldn't solve the issue, just alleviate it a bit. Though I wouldn't try, older CPU's are limited when it comes to overclocking as well as a lot more complex as you have to balance the RAM as well.
Seems you just have to grit your teeth until you can afford a platform upgrade.
Lower some settings that are more CPU biased. Tweak with the settings until you find something that's playable.
thanks and will have to do that until I get to upgrade