With the recently released KDE Plasma 6.1 desktop environment, those still relying on old Intel integrated graphics should have a much more pleasant experience thanks to improvements made to the KWin compositor. For very old Intel integrated graphics, it can effectively be a night and day difference upgrading to the new Plasma 6.1 desktop.
KWin lead developer Xaver Hugl is out with a new blog post about the improved KDE Plasma desktop performance as of Plasma 6.1, which can be especially noticeable with old integrated graphics hardware such as the common Intel graphics in aging laptops. The biggest improvement to bettering the KDE Plasma desktop graphics performance is thanks to dynamic triple buffering support.
KDE has been very good on my Intel 5300u laptop.