Afraid I’m not a CCP ocifionado :-/
Tick for a small calculation like this will not use resources. You’ll find it a much more elegant system, once you get it working 
All you need to do it set the ‘new max speed’ and the interp will shoot right there.
Not at a machine right now, but on that tick node, it’s just
Tick → finterp → set character max speed
I should be able to check it out later…