[Alps switch] Return rate too slow
Is this a problem for you when typing, or only for some kind of performance video-game context? Which Alps switches specifically are you talking about?
By “return rate”, do you mean they’re not stiff enough for you, or the switch actuation point is too high in the stroke, or something else?
If you think the spring is too soft, you could always try putting a stiffer spring in, e.g. using the springs from black Alps switches in your green Alps switches, or the springs from Matias clicky switches in your Matias linears.
If the issue is the actuation point, then that’s probably mostly down to practice and what you’re used to. The key will return plenty fast if you’re not holding it down.
If your typing speed is getting slowed down dramatically, there’s something funky going on. Plenty of people can type 100+ wpm with various types of Alps switches.
Some old Alps switches in bad condition have some dust/grit inside the switch, and can stick on the upstroke. This is not a built-in feature, but a result of storage on some dusty shelf without a box for 20 years.
My only issue with Alps boards is the spacebar. A faster return rate would do nicely there, or at least some more stabilization. Most spacebars only have one of these on one side: http://i.imgur.com/NFmrBYL.jpg and as a result they feel slow and take a while to return, slowing my typing speed.
If the spacebar is sticking, then there might be some gunk holding the stabilizer back. A lot of these peg stabilizers were lubricated at the factory, and 20+ years later the lubricant gets a bit tacky. Other times, the plastic of the stabilizer peg has been abraded a bit, and has a rough surface which catches. If you clean the stabilizers (peg, peg holder, and optionally the wire and wire clips) and then re-lubricate them, it can help smooth things out.
Some Alps keyboards have a spacebar switch with an extra-stiff spring, an external coil spring around the stabilizer peg, or even a second dummy keyswitch to return the spacebar. If your spacebar isn’t returning even after you clean and lubricate the stabilizers, you could try to find such an external coil spring to add.
My personal opinion is that any spacebar longer than 5 units is an absurdity, and all the work to stabilize ridiculous 7+ unit wide spacebars is a huge waste. Standardish-layout keyboards would be a lot better if they used split 2.5x1.5 unit spacebars instead, with keycaps shaped like the ones on the Matias ErgoPro.