Question: Currently I have a php script that external sites access with a api key. Based on the api key it returns data back in json. I been reading up on nodejs and feel this might be a good use of nodejs since I have noticed a high load/access of the api, though Im still new at this so might be wrong if I am wrong let me know. My question is in my php script I do a lot of checks to determine what information to pass back, using nodejs should I be doing all the checks using javascript or can I still use php with nodejs to extract the information needed to pass back as json?

**EDIT**

the PHP script/API consists of mysql access if that helps at all

Answer: 
Well it sounds like nodejs would not be the route to go in this case. I will instead go the route of either file based caching or memcache along with continue research to improve the code and db indexes/queries.
I am commenting on the first answer, but it is actually possible to run Node.js on a shared host as long as you have shell access or can compile and upload a compatible build of node. This method uses a library developed by samcday on github (http://github.com/samcday/node-fastcgi-application) and allows Node to respond to FastCGI calls. You do not need to be able to bind to a port on a public IP address and this will work with a virtual host.