>Nothing can be 10 times slower, that's impossible, but it can take 10 times the time to execute. What you mean to say is that it is one tenth of the speed. I have many years of advanced math from high school, and my teacher would have turned over in his grave if he heard '10 times slower'. When you multiply any positive value by a value higher than one, you always get a higher value. So technically '10 times' and 'slower' is a contradiction, or at lease they don't belong together. Just like '10 times less' or '10 times smaller' also are samples of wrong use of words.
I think that "slow" doesn't mean a thing per se (just like "fast" doesn't), it's the implied comparison that does. Things are perceived as slow or fast when compared with some (customary, or even imaginary) measure. My machine was fast, when I bought it. Now it's not, even though it's the same machine, and I've added memory and a faster disk. It is actually faster than it was, but it's not fast. Why? Because it's two years old, and it compares badly with the hardware of today.
So, "faster" and "slower" require comparison, and to compare, we use some units of measure. For "fast", it's m/s (not m/sec, as some would write - check SI standards), or MIPS, or benchmarks, or "guy A can down a 0.5l mug of beer in 8s, and guy B in 16s, so guy A is twice faster than B".
"Slower" would be just the reverse, i.e. the same comparison but favoring the other party. In the case of beer ex-ing contest, "guy B is twice slower than A". In general, we can take the "n times slower than" to mean "with speed n times less than". And I'm actually happy that people are saying so, it means that the ancient art of dividing two numbers in their heads hasn't completely vanished :).
Disclaimer: I wrote this while recovering from six urgent builds within just four hours... so I needed a slowdown. Thanks for a nice distraction :). Next time you get riled up about something, I may be on your side... depending on what it is.
Homework: define slowup.