Many organizations have used a "fix-it-later" approach to performance. This approach advocated concentrating on correctness and deferring consideration of performance until the testing phase. Performance problems detected then, were corrected by adding additional hardware, tuning the software (usually in a crisis-mode), or both.
Because it is based on several performance myths, this approach can be dangerous. These myths include:
Performance problems are rare: The reality is that the number, size and complexity of systems has increased dramatically and todays developers are less expert at dealing with performance than their predecessors. As a result, performance problems are all too common.
Hardware is fast and inexpensive: The reality is that processor speeds have increased dramatically, but networks are far slower. Furthermore, software threading issues cause performance problems despite the availability of hardware resources. No one has an unlimited hardware budget, and some software may require more resources than the hardware technology can provide.
Responsive software costs too much to build: This is no longer true thanks to SPE methods and tools. In fact, the "fix-it-later" approach is likely to have higher costs.
You can tune it later: This myth is based on the erroneous assumption that performance problems are due to inefficient coding rather than fundamental architectural or design problems. Re-doing a design late in the process is very expensive.