The website loading time may vary from one day to another because of different numbers of visitors or internet access or the server load (on server there can be several websites and their total number of visitors will vary each day). Also, the traffic on internet may vary each day and some devices for that network accesscan turn down or becoming faulty (they will be replaced when necessary but a faulty one can mess your access). Check your public target considering people's age and location and move the website on a closer server. The difference of time loading may vary with only one second if the server is USA and the public is in Romania (for example) but each second counts when you become viral and you have a huge number of visitors each day.
The total size of your content also counts. Usually, the size of the website should be as low as possible. The images should very visible, their quality as big as you can but their sizes should be low. When a website owner is posting each day and each post have images greater than 1 or 2 megabytes each and several images per post the total website size becomes huge for a smarthpone visitor with bad internet connection. So check the files size each time you are loading them on server and try to use videos on your website only when have enough memory and hard disk on your server and the account you have on webserver has a very good non-stop internet connection. Youtube is bad platform because it belongs to Google / Alphabet but it has a good connection and enough resource to play the videos pretty nice.
