I was hoping I could help you improve your wifi performance, but this is a rather poor adapter that is no longer supported by Intel. There is a chance that you may be able to improve the performance somewhat by testing different driver options.
Sadly many people don't get a lot of improvement, but you can try this:
Create the driver options configuration file:
/etc/modprobe.d/iwlwifi.conf
With the following content:
options iwlwifi 11n_disable=1
options iwlwifi swcrypto=1
options iwlwifi power_save=0
options iwlwifi d0i3_disable=0
options iwlwifi uapsd_disable=0
Save the conf file, and exit text editor.
Then reboot.
If there is no improvement after creating the options file then you can delete the conf file (and consider buying a replacement adapter).
Best of luck.