I think there should be a feature where you can search inside a specific topic, so it would only search for posts in the topic that you are currently reading.
For example, with the music thread you could search for a song to see if it has already been done. It could also be used for things like unreported service issues thread to see if anyone else has found that bug.
There are a few things that could be done to do this but none of them are brilliant solutions as they are not always simple, for example: Will suggested increasing the amount of posts per topic you see and then doing Ctrl + F to search for something on the page, but there is still the downside of it spreading onto more pages and it will still take time to do.
Spacerat suggested using a custom google search, but you can't really make one of those for every thread.
So I think giffgaff should introduce this feature as it can solve a few issues, it will also not affect people if they don't want to use it.
I am not sure if it will be supported by Lithium but will suggested I posted it here first to see if it is wanted