Indexing should be a low ressource task.
Thus it should use low priority for this (virtuoso use this nice 19) but also use ioclass idle in order to not disrupt other io bound process (not done).
We don't use virtuoso/nepomuk in 4.14
I will close this bug report
I am sure it could also apply to baloo and other indexer. Have you checked io class ?
Ok checked fixed