Here's a pic of a 2006 TT-R250V, the last model year sold in the USA:
Here's the remains of the Yamaha USA website page telling about it:
http://www.yamaha-motor.com/sport/products/modelspecs/34/0/specs.aspx
It's an air-cooled, 4-valve, dual overhead cammed, counterbalanced, electric start, 43mm forked, aluminum swingarmed, single shocked with remote reservoir, 6-speed, disc braked, knobby tired off-road bike.
It came to the USA in 1999, but was on sale in Europe for a few years before that as a dual-purpose (on/off-road) bike, and when it came to the USA, the street-legal parts were simply left off.
As far as performance goes, it's basically the Yamaha version of the Honda XR-250R with electric start instead of a kickstarter.
You get about 19 or 20 horsepower at the rear wheel at it's maximum.
The WR-250R gets about 25 horsepower at the rear wheel.
The WR-250R has to meet EPA and DOT regulations, so, yes, it is choked-up a bit.
Some basic mods - the same kind of mods done to other bikes that come choked-up due to EPA regulations - can have it running noticably better with better throttle response.
The WR-250R weighs about 25 pounds more than the TT-R250V because it has to carry a lot more parts due to regulations that make it street-legal and EPA compliant.
I can easily see why somebody would call the WR-250R a slow bike.
If they ride another bike with more CCs, or a bike that makes more horsepower and torque, the WR-250R will feel pretty slow, especially if it's straight off the showroom floor and not uncorked.
I know this first-hand because I was riding a 440cc 2009 Suzuki DR-Z400SM when I bought my 2008 Yamaha WR-250R, and that WR-250R was stock and had 113 miles on it.
In all honesty, the WR-250R felt as slow as molasses in comparison, and I believe it was because the 440cc DR-Z was the only thing I'd been riding for the last 9 months before that.
So, sure, the difference was dramatic upon the first ride.
By comparison, the WR-250R felt like it had no low-end power, had to be revved to the moon to get anywhere, and it simply felt stiffled and all corked-up for air and fuel.
I geared the bike down (because they come geared way too tall in my opinion), did the mods that are all over this message board, spent some time on the bike, and really came to appreciate it and like it.
Once I sold the DR-Z, the WR-250R became my street bike, and since I was riding only that on the street, it felt plenty fast with decent low-end and very good midrange and top end power.
For a 250cc bike that's street-legal, I believe it's as good as it gets as far as power goes.
The WR-250R is going to turn more RPM on the freeway at 75mph than a bigger bike will.
That's how it is.
For a 250cc bike, it actually turns relatively low RPM on the highway because it comes geared taller than is ideal for the amount of power the bike makes.
I believe that if you were to think the WR-250R was spinning too much on the freeway, you need a bigger bike that has that natural ability to be able to do 75mph at what feels and sounds like low RPM.