Yes, that would be metalayer-crawler. Each time your tablet is booted, metalayer-crawler should scan the entire tablet--including the SD card--for media files and index any found for the Media Player. Additionally, each time you insert an SD card, metalayer-crawler should check and index media files on it.

Some users have reported cases where metalayer-crawler has become confused by malformed media files or unusual filesystem layouts. In these cases it can get stuck, just spinning its wheels, and never complete the indexing. A side effect of this happening is the battery life of the affected tablet will plummet, as metalayer-crawler is keeping the CPU busy with unproductive work.

Some folks who run into this problem disable metalayer-crawler on their tablets. The downside, of course, is media on their tablets is no longer indexed for Media Player's use.

You haven't disabled metalayer-crawler, have you?