Historically speed mattered. The Rothschilds knew that Wellington had won Waterloo well before most of the London market. Whether they actively encouraged stories that Napoleon had won is open to discussion. But knowing Wellington had won meant they could buy undervalued assets. Speed of this type is not a separate Advantage to my mind, but a subset of Informational Advantage
However there is the advantage of the High Frequency Trader where they use the speed of their transactional system to front run the market to get their buy or sell in before other traders/investors. It has become increasingly expensive to get into this market but given the amounts being spent the advantage must still exist. If you have not already I do recommend Micheal Lewis’s “Flash Boys” on this area.
I do see front running as different to the historic informational advantage as there is no reference to an underlying asset simply the ability to trade a security that you have an understanding of demand for, because other investors are already trying to buy or sell it.
I personally regard this as parasitic and not that removed from insider trading, but it would be remiss to ignore its existence.
The other factor I would put under speed is the speed at which you learn from your mistakes.
I am not sure which investor said “I try to learn from my mistakes and not repeat them more than 7 or so times” but it is a truism. Most of us do not learn quickly from our mistakes and repeat them, often many times.
Psychologically this is because most of us have a predisposition to (a) mute bad news particularly when it comes to a mistake we have made (b) see our past selves as separate from our current selves and as such see our past selves mistakes as not relevant to our current selves actions. As such we do not learn from mistakes we have made nearly as well as we should.
This failure to learn is intertwined with the “opposites” bias, in which we swing from one extreme to another. We have all heard that most investors in any fund make nothing like the fund return because they switch in and out of the fund leaving it when it is low and then buying in when it is high. This bias occurs in so many ways with investing where the lesson taken from an event is to do very much the opposite of what was previously done, rather than a more effective, but often moderated, strategy. In the fund in, fund out strategy this might be scaling in or out rather than completely exiting or buying a large position in only one transaction.
The ability to learn the correct lesson from a limited number of events and then apply that lesson is a potential key advantage open to most investors, but perhaps surprisingly often not enacted as fast as you would rationally expect.