SFB is a much slower game than many other space combat systems, but nowhere near that slow. I have been able to both teach the basic rules to SFB and play a complete duel in under 2 hours. Whether SFB will be a good fit for you depends on how you react to the rules that slow the game down.

1) Energy Allocation: Like all Star Trek derived games, most functions require some power to operate. SFB has many more potential items to power (each often with multiple options) than other games. While the ability to micromanage ships operations can be fun, deciding what the optimum ratios of what to power can frequently take a lot of time.

2) Impulse movement: SFB breaks the turn into many smaller sections and permits the ship to move only one hex at a time. Obviously, having more individual movement decisions increases the time necessary to carry out those moves. However, this makes it much more difficult for one player to gain a very good firing position without risking the opponent getting one as well.

3) The Damage Chart. SB uses a very complex damage table to determine what parts of the ship get damaged. Each point of damage requires a separate die roll. With close to 100 points of damage needing to be applied to the 60's TV ships, this as you might expect takes a long time to resolve. However, the more common roll per weapon hit often turns the game into a more extreme luck contest. Numerous die rolls tend to even out over time.

In short, if you want to play out small fights and have a maximum of control over your ships, SFB is the best choice for you. If you want to play out very large actions with lots of ships, other game systems will probably be better choices. (And if you can find a copy of SFB's introductory products cheap enough, you should pick it up anyway. Several of the new space combat systems have been design to correct the flaws in SFB. Having some knowledge of SFB will make those designers decisions easier to understand.)