After some of the automatic updates in Win10, my Google based browser started to have typing lag problems with this forum and even though I have done a reasonable amount of work trying to track it down, I have not found out why yet. It also happens on Google Chrome so it may be a problem with Chrome based browsers as Slimjet is based off Chrome. I have tested Microsoft Edge and it does not display the problem so I suspect that Microsoft are up to some of their old trick of long ago that they used on Netscape to try and force more people to use the old IE.
In the short term it looks like I will have to use Edge so I can type into the forum, what I have been doing for a while is typing the post in a text editor then pasting it into the forum. I don't have to do this with Edge, even though it is a weird thing to try and set up.