Kerdios - That won't help your progress all that much. You'll eventually reduce the energy needed on those skills naturally, so try not to focus on just the first skill. Kill higher bosses, and eventually challenges and you'll be much better for it.
Kain - The easiest way to think of it is as though it were a linear progress bar. However, the progress is not based on the actual quantity of antimatter you have, but rather on the order of magnitude of the amount of antimatter you have. For example, 1,000 antimatter probably gets you close to 1% here, while 1,000,000 gets you close to 2 (rounding for simplicity). If this was based off the standard percentage, both of those would be about 10e300 shy. Take the exponent, divide by 306, and you've got your percentage on the bar. It drops when you buy a ton of dimensions because you are spending your antimatter so fast that you are actually dropping orders of magnitude. Hope this helps.
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 "Antimatter Dimensions"){kind=icon}