If your application really has to have accurate reliable timing then you
will need to write a real time application and install a kernel built with
the PREEMPT_RT patch https://rt.wiki.kernel.org/index.php/Main_Page otherwise you will be subject to the type of problem you are
A 256GB SSD drive can make an old laptop leap to life. Most slowness in
laptops is not because of a bottleneck for CPU time, but a bottleneck
accessing the disk. The SSD will not fix your DVD problem, but it will
make Scribus run faster.