I forgot to ask - what vintage?
My current hardware is not a good point of reference - but 90 seconds seems "too long" to boot up. However, if it's been that way from the time you acquired it, be happy there aren't other issues (yet).
I would get Tech Tool Pro 5 ASAP and run tests on memory/HD, etc before it deteriorates or goes west for good.
Back everything up before it's too late.
Good luck.