I drive a '91 Honda Accord. It’s still a great car.
Among other old programs, I use Photoshop CS4 and even have a PS plugin that lets me use my old 32-bit Photoshop plugins in my 64-bit install of Photoshop.
I never experienced any Selection lagging. But then I have always followed the hardware and software requirements of the programs I want to use. In SU’s case, that means exceeding the minimum hardware requirements for SU - which means my computer has a 100% OpenGL 3.0 compliant, dedicated graphics card (NVidia.) The MB integrated Intel graphics isn’t used for anything.
Integrated Intel graphics have a long history of iffy OpenGL support. Prior to SU17, SU’s reliance on OpenGL support from a graphics driver could be bypassed by disabling hardware acceleration in SU, meaning the program only uses the CPU. Quite a few SUppers clamor for better performance so SU17 upgraded its OpenGL requirements from version 2.7 to 3.0 and dropped the ability to bypass deficient graphics drivers to best meet the demand for more features and better performance (graphics cards with onboard, custom RAM and compliant drivers “enhance OpenGL performance upward of 3000 percent.”)
Drivers (and OS) are proprietary property of a manufacturer/developer. Just as all old OSs (i.e., XP, Vista) and old programs are not supported and updated, the same applies to older generation Intel graphics. What complicates Intel driver support is that computer manufacturers may tweak a driver to best work on the computer they sell - which may somehow compromise/remove some OpenGL function calls required by SU.
I don’t run out to buy the latest and greatest, rather I wait until the hardware wears out. That means I sometimes cannot update programs/apps. For example, waiting until last summer to upgrade the Nexus One phone Google gave me because it still worked even though the OS couldn’t be updated for several years and an increasing number of apps could not run on the older version of Android with its limited phone memory. So I just lived with what my hardware could do until it’s was time to get something new: which also better supported the latest and greatest apps. The unlocked Pixel with 128 GB memory I now enjoy is definity an improvement, but I managed to exist just fine with the old phone.
Getting back to the OP, @Petec , wanting a web version of SU to work offline is actually a feature request to have SU Free officially support offline use. It’s an oft repeated, reasonable request and should happen in time. Until the developers provide that feature and others critical things you want, SU has downloads of SU15-17 Make. Keep up with this sort of request as it help to mold the features and functionality of SU Free.