I suggest that we remove this tag. The presence of this tag makes users tag questions badly and causes severe inconsistency in tagging. The questions tagged with computer-science belong to several different areas. To get a feeling of the problem, it is like having a math tag and having users using it to tag question from different areas (algebra, analysis, logic, etc.) and just with it.
Right now the questions tagged with computer-science tag belong to several areas including:
There are many questions with computer-science that are tagged insufficiently (my rough estimate is more than half the questions with computer-science fall in this category). Similarly there are many questions tagged with one of the tags from the list above but not with computer-science.
So IMHO not only it is not effective for filtering/searching questions, it is in fact harmful because it allows people to get away with a improper tagging of their questions (which, in place of making filtering/searching easier, makes it more difficult).