I don't even know what people mean when they say holding blue fire or sacred fire.
I'm also referring to the mound of snow near a wall that would completely bypass a curve but I never seem to get distance.
It has to do with an unfortunately arcane system within the game relating to turbo pads. Basically, when you hit a bunch of perfect boosts while drifting, you build up an invisible gauge known as your 'reserves' or 'boost reserves'. When you have reserves, the turbo/boost that you get from a turbo pad lasts longer. Your reserves are constantly draining, and so must be frequently maintained with more boosts for them to last. Braking will kill your reserves. Hitting or even clipping obstacles will kill your reserves. Getting wiped out in any way will kill your reserves. Maintaining reserves at high speeds is navigating an obstacle course at breakneck speeds, but with more practice, you'll find yourself in the zone and able to maintain the speed from turbo pads indefinitely. It's also a mandatory skill for a couple of Oxide's time trials.
Oh, and turbo pads themselves are not created equally. Unfortunately, there's no visual distinguisher on the pads themselves to tell which gives what speed, you just have to learn through experience and commit them to memory. Most aren't out of the way. Anyway, there are three-ish levels to pad speed:
One is known as 'sacred fire' (an utterly unhelpful name to anyone trying to learn, but I didn't come up with this stuff. I just call it red/orange fire), which is the most common turbo speed you'll get on most tracks. You can tell when you have it as the fire spitting from the back of your kart's pipes will be bigger and more constant, and you'll find yourself going faster than you would from plain drift boosts. You can also get this kind of turbo by activating a turbo power-up when you have 10 wumpa fruit, allowing you to achieve it even on tracks with few or no turbo pads (such as Slide Coliseum). This is the base level of turbo you'll want in order to clear that curve gap on Gingerbread Joyride. You can probably clear it with a well-timed drift turbo and a well aimed jump, but that's a lot riskier and more difficult, like with the river jump on Blizzard Bluff.
The second level of speed is called blue fire or maybe 'ultimate sacred fire' or some rubbish. It's called blue fire because it makes the fire from the kart's pipe's blue. Very easy to see, if the speed didn't tip you off. These are less common and more valuable to maintain through drift boosting. With these, you can get some crazy air and perform unlikely cuts across gaps on the tracks.
The fastest pad speed is called... I dunno, super-duper blue fire? It looks the same as the regular blue fire, but it absolutely does not feel the same. It is notably faster. The most obvious example of this speed is on Tiny Temple, where it is given by the final turbo pad jump just before the finish line. That track is really good for practicing maintaining and controlling it, as you'll need to do so for two nearly-full laps in order to beat Oxide's time there.
In short: you want to do a lot of perfect boosts and avoid hitting obstacles to make turbo pads last longer. Since you tend to get bigger air while going faster, this is where airbraking becomes a real godsend. Oh, and there might be other intervals of speed between those three, but I haven't done the science and can't be certain.
But that's all advanced stuff. Don't feel like you've got to learn it now, just ease your way into whatever you're doing. And if you lose enough times in online, the game
should match you with less insane players and give you a better experience. It's just a pain to get to that point.