I assume you mean wind at 90 degrees to track, rather than 90 degrees to heading? This would be a far more useful scenario - and it makes a difference to the results.
Wind a constant 90 degrees from track, airspeed constant - as the windspeed increases, the groundspeed decreases.
Wind a constant 90 degrees from heading, airspeed constant - as the windspeed increases, the groundspeed increases.
(Actually, I was typing a reply agreeing with FD, when I noticed this subtle error. FD says, with respect to the wind being 90 degrees from heading, that "The net result will be that you will go slower forward in your track direction". This isn't true - but it's subtle enough that I didn't catch it until I actually tried to draw it so that I could describe how to prove it!)
FFF
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