Felix Miata wrote:
> I have a computer without SSE3. It runs Fedora just fine. I
initially had
> 1 GiB of RAM in it, I upgraded it to 3 GiB.
I have approximately 40 Fedora installations on 32 bit CPUs. About half of
those are on Prescotts. I'm unable to notice that those with more than 1G
RAM run any better than those with more RAM.
There are mainly 2 reasons I had to upgrade the RAM:
1. Akonadi / KMail 2.
2. "Modern" websites with massive abuse of inline images.
Both of those eat lots and lots of RAM.
I am able to notice that the older, slower ones that do have SSE2 are
able
to run, but with Plasma 5, those are very slow. Those do run respectably
with lighter WMs/DEs.
The main limiting factor there is probably not the CPU, but the GPU. If your
GPU does not support OpenGL 2 (OpenGL 1.x is not enough because GLSL shaders
are required), then QML 2 and thus Plasma 5 will fall back to software
rendering through the llvmpipe, which of course on an old CPU is not
impressive speed-wise.
What might help is disabling all the animations that can be disabled.
For those without SSE2, Plasma 5 is completely unusable, but OK with
any
of the lightweights.
Without SSE2, you additionally also lose the QML/JavaScript JIT in QML 2.
(There is no implementation of the JIT for the 387 FPU instructions, only
for the SSE2 ones.) So you also get an interpreter in C++ there. (At least
there IS a fallback, unlike in V8 and thus Chromium/QtWebEngine.) And of
course the llvmpipe will also be slower without SSE2 instructions. And they
will contend the CPU. There is not much Fedora can do about that, it is a
result of the design choices in upstream Qt.
Kevin Kofler