I've been tasked with arranging performance tests for a Web application to measure response time and memory consumption in different load scenarios.
However, our current test environment is shared across many test teams. This is acceptable for functional tests but I guess for performance tests I may get results that will be false. E.g., spikes in response time caused by other people interfering.
Creating a separate end-to-end test environment seems an expensive option now for many reasons, so I wonder whether such environment can give any, even rough picture of environment performance? What kind of tests or performance measure could be investigated with environment that is not isolated?