I have 4 GB RAM but still my server is very slow

you need to at least look at the processes in task manager to find out if it is the scraper or the database that is chewing up the cpu.

if it is the database, then you may benefit from a cpu upgrade, but more likely from tuning the database properly.

if it is the fetching process, then you need to give serious thought to it's architecture. i say this because you ought to be able to do sufficient fetches to overwhelm the database and disk io before getting anywhere near 100% if the program is efficient.