Though I have actually tested this to some degree, I've never really considered it to be a significant issue. The theory is based on Newton's third law - that for every action, there is an eual and opposite reaction, which in this case, is concerning momentum - the offset of the projectile*it's velocity has to be accounted for in the motion of the ship. I disagree that this is so. Here's why - it depends on the cannon in question. I'm assuming that the majority of such cannon were mounted on a rolling carriage. If so, the majority of the recoil of the carriage (the force of which is the same as the mass*velocity of the projectile), if absorbed in the recoil, which is retarded by friction on the deck, and fully stopped, if necessary, by the rigging, which has some elasticity, and therefore doesn't impart the full stopping force on the ship. So, you see, much of the resultant force is dispersed in the recoil of the carriage, so the boat is not significantly effected. Of course, if the guns were yoke mounted, there would be no recoil, so all of the resultant force would go directly into the ship, possibly resulting in retarding or accelerating it's motion.
Of course, all that said, I will go back to my first comment - I have tested this to some degree. What I meant by that is I have fired 1.5" bore cannon on wood and metal hulled sailboats up to 55' long. In doing so, I never saw fit to use rigging, so I can't fully describe to effect it may have had, but allowing naval carriages to recoil freely, they generally stopped about 1.5-2' back from their firing position (furthest ever was around 3' due to a slicker deck surface). When firing, most of these were being fired from the topdeck on either side, but sometimes from the bow, and occasionally directed forward. The shots when the cannon were directed forward, there was no discernable effect on the boat, either in speed or in pitch. The shots directed to a side at times could be felt to induce a slight roll, when the waves were light, even a little yaw when fired to the side from the bow - again, only when the waves were light, and the boat wasn't at speed.
Given the slight effect felt from the small guns, I'd love to test the larger ones, but I still don't think they'd have a significant effect on the ability of a ship to catch up to another in a chase-down situation. A bigger factor is which ships are involved. Typically, one of the ships will be a faster vessel, and whichever is will have the advantage, with or without any cannon being fired. For instance, consider a typical pirate vessel vs a merchant or war ship. The pirate vessel is usually going to be significantly smaller, faster, and more agile than a merchant or war ship, which will probably have significantly more and heavier guns. If the pirate vessel is attacking, it's coming up quickly, and firing at the rudder of the larger ship to attempt to immobilize it, however, it's main purpose of firing at this point is just to let the merchant vessel know that it is attacking (most pirates weren't so bold, as being so often resulted in their demise). In this situation, the pirate vessel is significantly faster than the larger ship, but also significantly less armed, and won't keep firing unless in an outright battle, so as to conserve it's resources, and only when within range, at which point, it's speed will allow it to easily overtake the larger ship regardless. Now consider the pirate ship fleeding the merchant ship or the war ship. It can easily out maneuver the larger ship, and it's significantly faster, so the merchant or warship firing upon it is in effort to stop it to allow it to catch up. If it can't disable the smaller ship, it will get away. Of course, it's cannon have more range, and probably are better supplied, so it can keep it up for a while, in hopes that it can halt the fleeing pirates. Again, in this instance, any effect the cannon has on it's speed is insignificant compared to it's ability to make speed.
