What's the most efficient usage of the golden mushroom in Mario Kart 64?

Okay, I've did some testing, and, it really doesn't matter much how you use it, as using a "pumping motion" (leaving a slight delay between each usage) or "pressing it as fast as you can" give both a direct boost to maximum speed, the item has a fixed usage time, and you can't double up on the boost.

HOWEVER, the most important thing, for efficient usage, is to always start your next boost before the speedboost effect of your previous boost has ended.

As a result, pressing it as fast as you can after 4 pump usages might give you the last boost closer to the end of the item, giving you a litle bit of extra distance, while still retaining the most control over your kart.

A final important thing to note is that unlike most other items, you can't pick up another item, while under the effects of the golden shroom.

I agree with George Stocker about using it to get through slower shortcuts, and also to knock around other racers. However, my personal experience seems to suggest that giving it a bit of time in between presses of the [Z] button seems to help maximize the boost's effect.

Of note is one of the reasons why I think it does so: It makes it much easier to drive. When you mash the [Z] button with the Golden Mushroom, the camera rapidly jerks in and out, generally having the effect of the player weaving all over the track. Even if using the boost more slowly does slightly reduce overall speed (which I personally doubt) it makes up for it by greatly increasing your ability to stay on the track.

Regardless, it still seems to work better with a delay even on a straight stretch of track. It seems that when the boost is used, there is a short period of acceleration up to the maximum speed, and that boosting repeatedly incurs this acceleration period each time.

However, I cannot prove any of this, and it should best be viewed as a personal observation, and taken with a grain of salt. If anyone can confirm this, please do so.

Hope this helps! :]

Ideally you want to use it to get around a section of track that would normally slow you down; grass, the not-so-deep water, and gravel are just a few examples. You also want to use it if you're a lighter weight character (toad, et. al.) against heavy-weights (Bowser, Wario). As far as what is 'better'; it only lasts for a certain period of time whether you hit it once or 100-times, so I'd use it more quickly.