I know that he can move very quickly (and even instantly). That's why when freeza says there are 5 minutes left till the planet explodes it didn't bother me that those 5 minutes took 11 episodes. Because of their high speed they can move super quickly and many episodes were needed to show everything. What I don't undestand is how they were able to give an enormous amount of speeches in those 5 minutes.
In the Dragonball series, in one of the tournaments, Krillin was fighting Master Roshi. They had a clash, which happened in an instant. No one saw what happened, so they acted the scene out in explaining in detail what happened. It included several attacks, and even a game of rock paper scissors. I don't know if its was in the manga or not, but it is solid evidence showing their speed. Even way back then, when large boulders were a challenge to deal with, they were still fast enough to, in an instant, play a game of rock paper scissors and know who won and lost, in the middle of throwing several attacks.
Later on in the series, we see higher speed fighting. Spectators see numerous shock waves filling their vision, each several meters apart. The fighters are attacking/defending in one place, then distance themselves and clash again dozens of meters apart numerous times in a very short period of time. This kind of speed is a higher leveled version of the Rock paper scissors earlier.
With such things as evidence, we can say it is very possible that they can talk at high speed when necessary. Sometimes, they do talk as they are clashing, though we only ever see that from their perspective, so we cant say for sure if they slowed down or not to talk. So while they at least somewhat can talk at a higher speed thanks to their insane speed and ability to comprehend everything while going at such speeds, they generally don't, and we don't have any solid evidence if they truly can.
But, there are other factors at play here. First off, Anime, even in the middle of canon fights, can and usually do throw in filler. They extend the fights to make the show go on longer, filling in more minutes with less story. There are numerous examples where people are exhausted in the middle of a fight, and yet later in the same fight that is still going on, they magically recovered, because of such filler. Some of that Frieza fight in the anime was filler, or canon scenes extended to fill more time.
Secondly, due to their vast speed, their clashes can be significantly faster than portrayed. Some times, they even count the seconds, and yet each time the count goes down can not only be greater than a second between them, but that time gap can even vary. When we are viewing the fights from the perspective of Goku, we cant possibly tell how much it has been slowed down for us to comprehend.
A third thing, specific to this case, Frieza held back, which caused the 5 minutes in the first place
In frustration, Frieza sends a Death Ball into the core of the planet, starting a chain reaction that would destroy Namek in five minutes (revealing immediately afterwards that he held back too much of his power for the Death Ball to be a complete success).
Its not unreasonable that his estimation was off by a few minutes due to his fear of being on the planet as it explodes, with an opponent he doesn't know he can win against. The wiki summary of the 5 minutes is also quite short, half the size of this answer, not a lot actually happened in those 5 minutes.