This article overshoots. Yes, Python is slow, and yes, all four runtimes cited are slow. As I've said before, I no longer believe the idea that languages don't have performance characteristics, only runtimes do, and as it happens, the decades-long efforts to speed up Python and their general failure to get much past 10-20x slower than C are a big part of why I believe that. NumPy being fast doesn't make Python fast; it's essentially a binding. A great binding that, if it meets your use case, means you can do great work in Python, but does nothing to help you if you don't need that stuff.
As for PyPy's "faster than C" performance, people really really really need to stop believing anything about a JIT running a single tight loop that exercises one f'ing line of code! Follow that link and tell me if your code even remotely resembles that code. In practice, PyPy is, I believe, "faster than CPython" with a lot of caveats still, but "faster than CPython" isn't a very high bar.
(Similarly, though another topic, Javascript is not a "fast language". People seem to believe this partially because of JIT demonstrations in which integers being summed in a tight loop runs at C speed. But this is easy mode for a JIT, the base level of functionality you expect from one, not proof that the whole language can be run at C speeds.)
There is no version of Python that will run you at anything like C or C++ or Java or Go or LuaJIT speeds on general code. It can't; for one thing you have no choice but to write cache-incoherent code in Python, to say nothing of the numerous other problems preventing Python from going fast. (Copious hash lookups despite the various optimizations, excessive dynamicness requiring many things to be continuously looked up by the interpreter or verified by the JIT, etc.)
I've drilled down on this one, but there several other "debunkings" here that are equally questionable. Python does not have a "great" concurrency story... it has a collection of hacks of varying quality (some really quite good, though; gevent is awesome) that get your around various issues, at the cost of some other tradeoff. The definition of "strongly typed" that Python conforms to is almost useless, because everything is a "strongly typed" language by that definition. In practice, it's a dynamically typed language, and yes, that can cause problems. Another collection of hacks are available to get around that, but they're add-ons, which means the standard library and other libraries won't use or support them. Yes, Python is a scripting language, it's just that it turns out "scripting languages" are a great deal more powerful that was initially conceived.
Wow, I must hate Python, huh? Nope. It's a fantastic language, certainly in my top 3, and still probably underutilized and underrespected despite its general acceptance. When I hear I get to work with it, I generally breath a sigh of relief! It is suitable for a wide variety of tasks and should certainly be in consideration for a wide variety of tasks you may have to solve.
But, it is always bad advocacy to gloss over the problems a language has, and all languages have problems since no one language can solve all problems perfectly. If you are doing something really performance sensitive, stay away from Python. If you've got something highly concurrent, think twice... your problem needs to comfortably fit on one CPU using one of the existing solutions or there's hardly any reason to prefer Python. (Yes, Python can sort of use more than one CPU but if you're going to do that you'll probably be happier elsewhere. "Just throw lots of processors at the problem" isn't generally a good solution when you're starting from a language that can easily be ~50-100x slower than the competition... that's still an expensive answer, even today.) Yes, it is dynamically typed and there are situations where that is OK and situations where it is counterindicated. In the long term, you don't help a language by trying to minimize the problems... you help by making it clear exactly what it is good for, when you should use it, and when you shouldn't. Otherwise, you convince a hapless programmer to pick up your solution, pour a year or two into discovering it doesn't actually do what you said it did, and now you've made an enemy for your language. Better for them to never pick it up because you truthfully told them it wasn't suitable.
That said, though, be sure your task is performance sensitive before just writing Python off... modern machines are really hard to understand the performance of and most people's intuitions are pretty bad nowadays. Dynamic typing has its problems, but so does static. Etc. etc. No easy answers, alas.
"Finally, slowness, until you get really low-down is relatively easy problem with many solutions."
There is a barrier that you can hit in Python/Perl/Ruby/Javascript where you're trying to do something, you've optimized the Python/etc. to within an inch of its life, and it's still just too slow. I've hit it twice now in pretty serious ways. Once you've removed all the slowness-that-has-easy-solutions, you're still using a very slow language... the 50-100x number I cite is with the slowness already removed for optimal code, though, to be fair, this is in comparison to fairly optimal C/C++ as well. Well-written Python can be competitive with poorly-written C, and that is also not even slightly a joke, since it's generally easier to get to the well-written Python. But you can still run out of juice on a modern machine.
But ultimately this is just something you want to know and understand, and not be too bedazzled by claims that everything's hunky dory in every way.
In my opinion, definitions of 'strongly typed language' and 'dynamically typed language' are orthogonal and Python is both. You can't say that Python isn't strongly typed because its dynamically typed. For example, C is staticly typed, but weakly typed at the same time.
I agree on the rest, though.
Edit: since a lot od people here are arguing what does 'strong typing' mean, I take it from what I learned at college: it means that, apart from typical conversions (like int -> float), it doesn't do many automatical conversions for you.
As for PyPy's "faster than C" performance, people really really really need to stop believing anything about a JIT running a single tight loop that exercises one f'ing line of code! Follow that link and tell me if your code even remotely resembles that code. In practice, PyPy is, I believe, "faster than CPython" with a lot of caveats still, but "faster than CPython" isn't a very high bar.
(Similarly, though another topic, Javascript is not a "fast language". People seem to believe this partially because of JIT demonstrations in which integers being summed in a tight loop runs at C speed. But this is easy mode for a JIT, the base level of functionality you expect from one, not proof that the whole language can be run at C speeds.)
There is no version of Python that will run you at anything like C or C++ or Java or Go or LuaJIT speeds on general code. It can't; for one thing you have no choice but to write cache-incoherent code in Python, to say nothing of the numerous other problems preventing Python from going fast. (Copious hash lookups despite the various optimizations, excessive dynamicness requiring many things to be continuously looked up by the interpreter or verified by the JIT, etc.)
I've drilled down on this one, but there several other "debunkings" here that are equally questionable. Python does not have a "great" concurrency story... it has a collection of hacks of varying quality (some really quite good, though; gevent is awesome) that get your around various issues, at the cost of some other tradeoff. The definition of "strongly typed" that Python conforms to is almost useless, because everything is a "strongly typed" language by that definition. In practice, it's a dynamically typed language, and yes, that can cause problems. Another collection of hacks are available to get around that, but they're add-ons, which means the standard library and other libraries won't use or support them. Yes, Python is a scripting language, it's just that it turns out "scripting languages" are a great deal more powerful that was initially conceived.
Wow, I must hate Python, huh? Nope. It's a fantastic language, certainly in my top 3, and still probably underutilized and underrespected despite its general acceptance. When I hear I get to work with it, I generally breath a sigh of relief! It is suitable for a wide variety of tasks and should certainly be in consideration for a wide variety of tasks you may have to solve.
But, it is always bad advocacy to gloss over the problems a language has, and all languages have problems since no one language can solve all problems perfectly. If you are doing something really performance sensitive, stay away from Python. If you've got something highly concurrent, think twice... your problem needs to comfortably fit on one CPU using one of the existing solutions or there's hardly any reason to prefer Python. (Yes, Python can sort of use more than one CPU but if you're going to do that you'll probably be happier elsewhere. "Just throw lots of processors at the problem" isn't generally a good solution when you're starting from a language that can easily be ~50-100x slower than the competition... that's still an expensive answer, even today.) Yes, it is dynamically typed and there are situations where that is OK and situations where it is counterindicated. In the long term, you don't help a language by trying to minimize the problems... you help by making it clear exactly what it is good for, when you should use it, and when you shouldn't. Otherwise, you convince a hapless programmer to pick up your solution, pour a year or two into discovering it doesn't actually do what you said it did, and now you've made an enemy for your language. Better for them to never pick it up because you truthfully told them it wasn't suitable.
That said, though, be sure your task is performance sensitive before just writing Python off... modern machines are really hard to understand the performance of and most people's intuitions are pretty bad nowadays. Dynamic typing has its problems, but so does static. Etc. etc. No easy answers, alas.