i'm just wondering why....

Hum, I don't even know Photoscape, but has this happened in another software ? I have just downloaded and installed this font, tried it in different software, it works perfectly fine. Maybe you should try to find a Photoscape forum to ask if this has happened to other users before, as the font doesn't seem to be the issue.

More than a Megabyte so what do you think?

I think it's because this font is too heavy (not the look but the size in kb).
It's not optimized, probably created "automatically" with a scan or something like that. It's look doesn't justify it's heavy size.

edit for typo. kk