a critical warning about Classic Timing Analysis

Right-click on the row and do a List Path. Then below in the messages you'll see a new line for that path which you can expand and contract, so you can get a detailed view of how many levels of logic this path is, what the clock skew is, etc. For the record, it's really difficult to have a path that is 295ns long. So either you have a ton of logic, or perhaps something else is going on. If it's really that much logic, you're going to have to add pipeline stages. (The case I've seen where you can get this much logic is when users write out lots of math calculations as a single line without pipelining. One of the main things FPGAs get their performance from is the ability to pipeline and run each section at the same time(assuming no feedback).