Yet More on PHP Scaling

Ian writes a scathing piece on PHP vs J2EE scaling here. His main conclusion is that "Common Stupid Mistakes" that cause scaling problems are platform agnostic. Naturally he goes on to describe some of these mistakes

1. Development shortcuts that are quick-n-dirty that also happen to introduce slow-n-dirty runtime characteristics (let's just call those "crappy hacks")
2. Insufficient use of caching or pre-generation of components that are static or have a low change rate (let's just call those "gratuitous dynamicism")
3. Inappropriate use of caching... does that logic need to be cached or is its invocation infrequent enough that maybe a plain old CGI is exactly how it should be implemented? (that'd be "gratuitous caching")
4. Excessive round-tripping to the database (well, that's just "excessive round-tripping")
5. Tight coupling of architectural pieces that have independent scaling and/or stability requirements... (score that: "tight coupling")
6. Nailing up resources i.e. does each child thread/process require its own database connection? (another potential effect of "tight coupling")