Sending webform for adding crucial information does not slow down (I had an unconditional LoA then when condition was lifted, I raised a webform and intimated them about the condition removal letter, then again after around 15 days sent another webform with Confirrmation of Enrolment).
Whereas webform saying "What is happening in my file I haven't heard from you in xx many days" for an application within prrocessing time will slow it down because as many people send this, the morre their VOs will be exhausted in looking at useless info. In the peak times, IRCC receives around 4k--6k webforms a day! I read it in an immigration lawyer's twitter handle.