[glapher]

For example I recently discovered I have the following:

Appleworks
Gbspotlightimporter
iwork
microsoft office
parallelsMD

What are they? What do they do and how can I remove them?

(I've heard somewhere that they can cause slow downs, is that accurate?)

[turtle777]

What could a Spotlight Plugin for Microsoft Office possibly do ?

Oh, right, helping to index Microsoft Office files.

Not sure what Gbspotlightimporter, but all the others are pretty much self-explanatory.
Sure you can remove them, you'll lose the ability to search for that specific content / files.

-t

[P]

Spotlight is a tool that indexes not only filenames, but also the content of files. For that to work it has to know the file structure. By default it knows a few standard formats - those plugins that you've found teach it a few more formats. If you remove them, you will no longer be able to search inside those files. If a plugin is corrupted, it will slow down indexing - if you have problems with the indexing process (mdworker) taking a lot of CPU time, those are potential culprits.

Appleworks, iwork and Microsoft Office lets you search inside files from those applications. Gbspotlightimporter seems to be for Garageband, and parallelsMD presumably let's you search inside disk images.