Comment 0 for bug 1797335

strstr() from glibc is up to 8 times slower than it was on ubuntu16. Looks like the sse2 optimized code is not used. To reproduce compile attached file (strstr.c) :

$ gcc -o strstr strstr.c

and then run on the 2 platforms :

$ vagrant init ubuntu/bionic64
$ vagrant up
$ vagrant ssh
Welcome to Ubuntu 18.04.1 LTS (GNU/Linux 4.15.0-36-generic x86_64)

 * Documentation: https://help.ubuntu.com
 * Management: https://landscape.canonical.com
 * Support: https://ubuntu.com/advantage

  System information as of Thu Oct 11 09:02:46 UTC 2018

  System load: 0.0 Processes: 97
  Usage of /: 9.8% of 9.63GB Users logged in: 0
  Memory usage: 12% IP address for enp0s3: 10.0.2.15
  Swap usage: 0%

 * Security certifications for Ubuntu!
   We now have FIPS, STIG, CC and a CIS Benchmark.

   - http://bit.ly/Security_Certification

 * Want to make a highly secure kiosk, smart display or touchscreen?
   Here's a step-by-step tutorial for a rainy weekend, or a startup.

   - https://bit.ly/secure-kiosk

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

0 packages can be updated.
0 updates are security updates.

Last login: Thu Oct 11 09:02:17 2018 from 10.0.2.2
vagrant@ubuntu-bionic:~$ cd /vagrant
vagrant@ubuntu-bionic:/vagrant$ time ./strstr aa
matches = 3000000

real 0m4.877s
user 0m4.852s
sys 0m0.012s
vagrant@ubuntu-bionic:/vagrant$

Same machine :

$ vagrant init ubuntu/xenial64
$ vagrant up
$ vagrant ssh
Welcome to Ubuntu 16.04.5 LTS (GNU/Linux 4.4.0-135-generic x86_64)

 * Documentation: https://help.ubuntu.com
 * Management: https://landscape.canonical.com
 * Support: https://ubuntu.com/advantage

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

0 packages can be updated.
0 updates are security updates.

New release '18.04.1 LTS' available.
Run 'do-release-upgrade' to upgrade to it.

Last login: Thu Oct 11 08:22:26 2018 from 10.0.2.2
vagrant@ubuntu-xenial:~$ cd /vagrant
vagrant@ubuntu-xenial:/vagrant$ time ./strstr aa
matches = 3000000

real 0m0.525s
user 0m0.508s
sys 0m0.000s
vagrant@ubuntu-xenial:/vagrant$
vagrant@ubuntu-xenial:/vagrant$ time ./strstr aa
matches = 3000000

real 0m0.525s
user 0m0.508s
sys 0m0.000s
vagrant@ubuntu-xenial:/vagrant$