I don't think I am doing anything unusual other than using a custom PatternParser and setting the lookup strategy to Find all matches. I tend to have 1-10 512MB files open with several searches per file.

Thanks for the update.

Parsing does not occur on the main UI thread, so I don't think that is the issue.  5 GB of logs would significant.  How many searches are we talking about?  You should be able to determine this by looking at the highlight manager.    Also, do you notice any difference when you have fewer files open or fewer searches?

Opening the highlight manager took 1 minute and 10 seconds to display anything. After that it was nice and responsive. Currently I have 13 highlights and 20 searches open. I currently have 4-5 512MB files merged. I am not sure if it makes a difference how much I have open but I have the impression it is a bit faster but still very slow when there is only 1 small file open.