If you are experiencing slowness when accessing your website at certain times of the day. You should start noting down the date and times that are you experiencing this issue. There may be a lot of different causes that could be causing your website to be slow.
If you are on a shared web hosting plan. You should make a note of the date and times that the slowness were taking place. After you have a list of days and times that this is occurring. You should contact your web host and let them know. Sometimes your web hosting provider may be updating the server at a specific time everyday. This may result in slow performance or slowness when attempting to access your site.
Another possible cause is another user on the same server is running a script or their script is doing something everyday that maybe causing the performance issues. When your web host gets a lot of complaints about slow performance. They will investigate and it simply maybe another user running a script that is doing things that it shouldn’t be doing.