The NSClient++ application has a small memory print when it comes to system resources. I have installed it and the software is running through a client that consumes about 2-5 MB of the RAM. It's running fast on a dual-core computer, for example. This is just a normal application. Yes, you can use it for a SQL server that's running 100 jobs or so. It handles the jobs and the queries pretty well. For more information, access the official website.