This has certainly been one of the on-going discussion points of the team during development. Although my background is in BASIC I have now almost exclusively migrated to PHP since I developed the website.
It is true that there always exists an algorithm which can solve the problems in less than one minute in a language like PHP on an old machine. My own PC is low powered and about seven years old and I can confirm that most problems I've solved takes less than one second. There are some problems though which take longer, but I've never come across a problem yet taking more than 20 seconds on my machine. Sadly the same algorithm using a compiled language on a newer machine could take milliseconds to solve.
This unfair aspect is amplified when you don't discover that neat algorithm in the first place and you develop a less efficient algorithm. Then members using a better language seem to "get away with it" and have no idea their algorithm is not as good as it could be. It might take several minutes using their language, but it would never solve in a sensible time using PHP.
In cases like this be assured that the team always set limits of problems such that the efficient algorithm should solve in the blink of an eye, but there exist at least one or two alternative approaches that will still solve in less than one minute using interpreted languages on older machines. As genious999 says, if it is taking a long time then there really are other approaches that will solve it quicker.
However, I understand your frustration s0ul-child, as on occasion the lightning quick times posted in the forums are less an indication of the efficiency of the algorithm as much as the speed of the machine and programming language. To add insult to injury I too have encountered those "fatal-errors" using PHP which other languages would not throw out. However, I can assure you that each problem has been extensively tested and with a little rethink of your current algorithm (or a complete rethink!) they can be overcome. At the end of the day it becomes more of a challenge to yourself. You have to accept that all things are not equal using a language like PHP, but that adds to the fun and will make you into a more critical and experienced problem solver.