The slow keying response is one of the performance issues, please try these suggestions below to check the result:
1. Run Outlook in Safe Mode:
Press Win + R, type "outlook.exe /safe" in the blank box, press Enter.
Then Outlook will start in Safe Mode, check if the slow keying resopnse issue persists. If no, then probably the issue is caused by some 3rd-party add-ins, disable the suspicious ones to verify which one is the culprit.
2. Disable the hardware graphics acceleration:
In Outlook, click File -> Options -> Advanced -> Display -> Tick "Disable hardware graphics acceleration".
This option is new in Office 2013, sometimes it causes some performance issues in Outlook, disabling it may help in this scenario.
Please note it's global in Office applications, if you disable it in Outlook, it's also disable in other Office applications like Word and Excel.
3. Perform a clean boot:
We can also perform a clean boot to determine whether background programs are interfering with Outlook, the detailed steps are introduced in the kb below:https://support.microsoft.com/en-us/kb/929135
I hope the information is helpful.
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