We tested your script and wanna to say it’s awesome.
you have one q&a about choice between host or vps, here:
there every thing is global, can you say heavy load means how much request per hour? or every thing about best select of plan.
As for hosting requirements, it’s hard to say because it really depends on what you process. Larger web pages will use more RAM and CPU, as will increasing the number of feed items you process in each request. The number of simultaneous requests the server handles will also affect this. So our suggestion is really to try it out and monitor the server resources to see how much is being used. If you use something like Linode, they will give you graphs showing CPU and memory use on the server so you’ll get an idea if you need more RAM or not.
Another way to handle the load, if you find that your server struggles to cope, is to set up more than one instance of Full-Text RSS. You can then spread the load using round robin DNS or other forms load distribution.