EventReciever as SandBox Solution

I am having an Event receiver as sandbox solution to perform certain action on item Added to the list. Basically it is creating a sub-site on item added using custom template. Problem i am facing is every time i am deploying the wsp, it is eating up resources and unable to create the site. Creating the sub-site code is taking too long time and resource quota get exceed from its limit. How Can i improve the performance of the solution.Reading through several articles i found instantiating the SPWeb, SPSite, SPListItem cause the issue. But in my solution i tried to obtain these object through "Properties".