Is it generally a really hard lag spike that happens every minute or so? If that’s the case, this is exactly an issue I have too but I’m not sure what causes it, especially considering the issue also happens sometimes when testing project in the actual UE4 editor.
Edit: You mentioned having no lag when standing still or noclipping, could you be having an issue similar to this? (this, at least for me, is unrelated to the every minute lag spikes thing)