No, performance issues are orthogonal to the method you use: if a participant’s browser is having a hard time running the script of the pages they are visiting, the whole execution of the experiment will be affected
The delays, as I said, come from the fact that every single command takes a non-null time to be executed, which means that even two consecutive commands cannot be considered to happen at the same time, so that a sequence newTimer(100).start().wait(),newTimer(200).start().wait() cannot be taken to last exactly 300ms with 100% certainty. The advantage of creating an overall Timer element of 4000ms is that you don’t depend on a sequence of commands to calculate its duration, and are therefore not at risk of accumulating such delays in doing so
Jeremy