I think you're asking for the wrong thing, which is why you're getting such a debate. You don't need a word processor, you need a text editor.
CygnusEd is good, but I'm not sure if it has a spell checker. For me, the best text editor was Protext (I have Version 6.1). I'm not sure if you can buy it, but put an ad out on Amiga.org & Amibench, you might strike lucky.
It's fast & doesn't slow down on long documents.
Wordworth (without the "s" after Word) is good, but is a WYSIWYG word processor and therefore, more resource hungry.
FWIW
