Thread:Extension talk:Lucene-search/Searching (spell.Suggest) too slow/reply

Do you have enough RAM for linux to cache the whole spell-check index in memory? If not, you might be hitting I/O which slows down things around 100 times. The size of your wiki shouldn't be an issue (it works fine on much bigger wikis like en.wikipedia.org).

You can also try to decrease the size of spellcheck index. Try settings like these: yourwiki: (spell,40,10)

And then rebuild your spellcheck index. This will index only those words which appear in at least 40 articles, and phrases in at least 10 articles.