As impressive as the Federation Fleet of Star Trek is, it's generally agreed that the Klingon Imperial Fleet is more deadly overall. Good thing it only lasted from the 22nd to 23rd century. While the Federation focuses on diplomacy, science, and exploration, Klingon ships are built for battle and conquest.
Speed is an important factor when you're waging a war of aggression, and there are a lot of fast ships on the Klingon side. Several Birds-of-Prey are on the list, as the standard speed for these types of warships is Warp 8.5.
10 IKS Klothos
The IKS Klothos was part of what was essentially the cavalry of the Klingon Fleet. It was one of the D-7 class warships that the Romulans would later adapt for use in their own fleet. These were actually designed to mimic the look of a manta ray. Fast and powerful, it also had a cloaking device, which was fairly new technology in the 23rd century.
It was frequently used as part of the classic "mousetrap" maneuver, in which three ships triangulate a single enemy vessel. The ship launched a successful attack on the Federation starbase and even attacked the USS Enterprise during a skirmish in the Delta Triangle. Luckily for the Enterprise, the Klothos was intercepted by the peaceful Elysian Council.
9 Commander Klaa's Bird of Prey
Commander Klaa was looking for a fight, and he got one when he decided to make a name for himself by tracking down and killing the USS Enterprise and Captain James Kirk. In Star Trek V: The Undiscovered County, Klaa starts his rampage by destroying the Pioneer 10 satellite. The pursuit eventually led to Nimbus 3 and finally through the Great Barrier to a planet called Sha Ka Ree, making it the first Klingon vessel to venture into this unknown territory. The pursuit was successful, in no small part to the ship's capacity for speed, and Klaa was only stopped by one of his superior officers, General Koord. He was on the Enterprise at the time after being liberated from the Army of Light and rebuked the inferior Klingon officer at Spock's insistent request.
8 IKS Negh’Var
The first warship in the fleet of this distinctive design, the IKS Negh’Var would inspire a whole race of ships, the Ngh'Var class, and serve as the flagship of the Klingon fleet. It led an armada of 50 ships on an invasion of the Cardassian Union and a similar attack on the starbase, Deep Space 9.
Due to its power and speed, it was charged with carrying Chancellor Gowron to safety when the Klingons were expelled from the Cardassian Empire in 2373. The ship also played an important role in the Dominion War.
7 IKS Korinar
A part of the advanced B'rel class that included both Klingon and Federation technology. Since they were developed during peacetime, these were Class 1 scouting vessels that were more about speed and exploration than battle. The ship served through the 23rd and 24th centuries and faced both the Cardassian Union and rogue ships from the Klingon Empire during the civil war. Its capabilities were tested during wargames with the federation in the Trexelian Expanse and it played a pivotal role in a secretive mining operation in the Bajoran system.
6 Duras Bird of Prey
The House of Duras was a powerful divisive force in the Klingon Empire. They had a hand in starting the Klingon Civil War. A large part of their power came from the fearsome Bird-of-Prey that dominated their rebellious fleet. This ship appeared in Star Trek: Generations when the Duras Sisters formed an alliance with the mad scientist Soran. The audience gets to see some detail of the complex interior when they take Geordi La Forge prisoner. Previously the ship was commanded by Duras, son of Toral, who used his more powerful ship to capture Jonathan Archer in the year 2153. It took three United Earth Starfleet ships to drive the Duras Bird-of-Prey to retreat.
5 IKS Gr'oth
One of the D-7 class Klingon ships, this class was so powerful the Romulans eventually adopted the model for their own use. The original design dates to 23rd century as an effort on the part of Chancellor L'Rell to unite all the feuding Klingon houses under one distinctive kind of ship. This worked in part, as the class formed an important part of the fleet that challenged Federation dominance throughout the universe.
The IKS Gr'oth was one of this class, as fast as it was powerful, a credit to this type of ship. Despite all this potential for fury, however, the vessel was admirably sabotaged by Scotti, who transported a small army of tribbles into the engine room as she was leaving Deep Space K-7 in 2268.
4 IKS Hegh'ta
An important part of the Klingon Defense Fleet during the Civil War, the IKS Hegh'ta saw a lot of action. It successfully defended the IKS Bortas from attack and fought alongside forces loyal to Chancellor Gowron. Worf of The Next Generation fame served on this ship as a tactical officer in 2368, and during this time the vessel was able to show off some of its fast moves. In a clever maneuver, she escaped two rebel Birds-of-Prey by jumping to warp within close proximity to a star. The resulting solar flare consumed and destroyed both enemy ships.
3 General Chang's Bird of Prey
Driven by his lust for battle and an affinity for Shakespeare, Chang seemed to channel his passions into his ship. This Bird-of-Prey was instrumental in assassinating Chancellor Gorkon and pursued the Enterprise quite successfully, playing a cat and mouse game that extended throughout the galaxy. It was not only her conventional design that emphasized speed that made her so dangerous but a new technology that allowed the ship to fire when cloaked. They were able to catch up to and attack her in an effort to halt the crucial peace conference that would save the Klingon race. It was the cutting-edge tech of the HMS Excelsior, with none other than Captain Sulu flying her at breakneck speed, that saved the Enterprise from Chang's wrath.
2 IKS Bortas
Just to clarify, this is not the 22nd century D-5 class ship, but the most modern 24th-century Vor'cha class vessel. This type of warship was the most powerful of its age until it was eclipsed by the Negh'var warship later in the 24th century.
This ship appeared in several episodes of Star Trek: The Next Generation as a ship allied with the Federation. Captain Picard contacted the vessel at one point to request reinforcements during a mission to discover a hidden Romulan military base. It once survived an encounter with a ship loyal to the House of Duras and acted as Chancellor Gowron's flagship during the Klingon Civil War.
1 Kurge's Bird-of-Prey, or the HMS Bounty
One of the most notorious Raptor class ships, Kurge was pursuing Kirk and seeking information about the elusive Genesis Project in Star Trek III, The Search for Spock. He believed it could also have been used as a powerful weapon and he was right. In fact, Kurge was right about a lot of things. He successfully used his ship to pursue, catch and very nearby defeat Kirk and take Genesis. In the end, Kirk managed to outsmart Kurge and took his ship. The story doesn't end there, however, as their next adventure took an unexpected turn. In Star Trek IV: The Voyage Home, their Klingon ship would be tested in a daring experiment to save all life on earth. The "slingshot around the sun" time travel method, which was successful, brought the Bird-of-Prey to a record speed of Warp 10.