You do not need to sign in. Please do not post duplicate messages about the same subject. Please search the forum before posting in order to make sure your question hasn't already been dealt with.
Your client is fully functional without ever even registering with BitComet Passport, much less signing in. This is not an issue for great concern when it occurs. It will not measurably affect your speed except in very narrow, very rare circumstances which are entirely hypothetical and un-proven.
When you are unable to sign in, this is not a matter for concern. Within a short time, you will be able to sign in again.
This issue is getting ten times the traffic it deserves. I am beginning to believe the whole idea should just be abandoned or closed off for non-Chinese IP's again, because people seem to just panic over an utterly trivial issue.