Exclude folder from search

I want to search a whole drive for something, but it spends ages looking in some folders I know are irrelevant such as Windows or Program Files, so I'd like to exclude these.
Using an advanced Find, I can add Full Path no match *\Windows* for example, and indeed it does not return any matching files in that directory, but it still searches the directory wasting time.
Is there a different way I can do this, or can the search be smartened up to ignore a folder that is excluded from results.
An example to be clear:
Find in C:
Find Name match *.txt
And Full Path no match *\windows*
will find and list all txt files in c:\ excluding those in c:\windows & subs
but it still searches the whole of C:\Windows & subs

Use sub-folder clauses to avoid entering a folder at all:

I had read that before posting but didn't understand it enough to use. I hadn't spotted SubFolder and that does indeed solve the problem, many thanks Leo.
According to that other post you mentioned though, using Full Path should pretty much do away with need for SubFolder. However it doesn't appear to work in this usage scenario.

You should be able to get the same results with either, but Sub Folder is more efficient because it stops the search progressing into the undesired sub-folders in the first place. Full Path will search everywhere but then restrict the results.