dpkg-deb error. Issue while installing in Ubuntu 14.04.5 LTS

I basically don’t know what I’m doing.

Lintian check results for /home/name/Downloads/package.deb: no entry control.tar.gz in archive  gzip: stdin: unexpected end of file /bin/tar: Child returned status 1 /bin/tar: Error is not recoverable: exiting now 

Tried to install anyway

dpkg-deb: error: archive '/home/name/Downloads/package.deb' has premature member 'control.tar.xz' before 'control.tar.gz', giving up dpkg: error processing archive /home/name/Downloads/package.deb (--install):  subprocess dpkg-deb --control returned error exit status 2 

Help is highly appreciated

UBUNTU 14.04.5 LTS APP RUNNING ON i9-9980XE TWICE AS SLOW AS OLDER, SMALLER PC

Is the reason that our new i9-9980XE, 128GB RAM, X-299 MB, 18cores is running the application on Ubuntu 14.04.5 in 10 hours versus and older i7, 64GB RAM, 4 cores in 5 hours because of the old kernel? What is the newest kernel that I can install in 14.04.5 and still have it function? The application must run on 14.04.5.