Question: **EDIT:**

Calculations were incorrect, the earth in my comic is not 5.8x larger, it is 2.4x larger. Its surface area is 5.8x larger but the diameter is 2.4x larger.

Anyway

I'm working on a comic that is set in an alternate earth that is 2.4x larger than the real world in an effort to incorporate numerous fictional locations that could not fit on a real-world map due to their sizes.

I am wondering if earth that is 2.4x larger would slow down human progress to a significant degree due to the fact that travel times would be extended, thus slowing trade, immigration, and colonialism. 

This comic aims to be set in a modern world albeit on a larger Earth. The USA still exists but it's a much larger country. New Jersey, for example, is now the size of England. Likewise, the repercussions of this larger earth may inhibit the USA from ever coming into existence. 

If the answers result in any conflict with the goals of the comic, I may just resort to pure fantasy but it will be fun to learn how this stuff works regardless.

Answer: 
Civilization is the inevitable result of agriculture: people needed to band together in a fixed location to protect their crops before and after harvest, and they need written records to track who owns what.

This happened on our Earth about ten thousand years ago in three places roughly simultaneously: Central America (corn), the Middle East (wheat) and the Far East (rice). As those early civilizations grew, they spread north and south in search of more land for their crops—and discovered other crops to farm in the more temperate climates.

Within about four thousand years, most habitable regions of Earth were "civilized". Since there was no more free land, continued population growth (also a result of agriculture) resulted in wars to take existing farmland from others, and empires were born.

(Notice that Creation is usually placed somewhere between those two bounds, depending on when each civilization was founded and thus the start of their historical records.)

On a larger planet, agriculture will likely be discovered at more longitudes, but there will be more latitude for civilization to travel (assuming a similar ratio of land to sea), resulting in a slightly longer spread from each origin. That might be easier, though, since the climate should vary more slowly, and maybe (handwave) that cancels out.

Empires depend on the speed of communication and armies, so at least prior to industrialization, they would probably be similar in absolute size to our historical ones. Once you have mechanized travel and electronic communication, though, all bets are off. OTOH, more people means technology should progress much faster, so they may not have spent as long in the pre-industrial era as we did.
A lot depends on how you want to define progress. Most answers seem to assume it is driven by population. But actually a lot of tech is driven by war.

In realistic terms conflict would take a lot longer to arise as humans populate the Earth before being dense enough to get into real conflict. Personally I think it's quite possible we may go extinct at one of the ancient population bottlenecks and Neandertals may still be around.

It's too broad a question to go into detail, but you could basically build several totally different stories from that same beginning.