How do I improve the release speed of a vacuum spring made from syringes

I have made a draft of a small projectile blaster that uses empty sealed syringes instead of conventional springs. The draw strength is phenomenal with two 20ml syringes, I've achieved about 5kg draw strength in a small form factor, but the release speed isn't nearly enough to launch anything. I've tried wd-40 for lubrication but it seems to have done the opposite effect and increased the friction. Is this a lubrication problem or is it the innate problem of vacuum springs? do I need to look more into mechanisms that trade strength for speed?