Outlook performance issues will affect your business in many ways. Ensure to follow the below steps if your users are reporting any outlook performance issue.
Basic Requirements to Access Office 365 Mailbox
Ensure User using Outlook 2016 or above and the Proxy settings configured properly
Ping outlook.office365.com and ensure it is resolving to nearby Microsoft Datacenter (local Airport Code). Chennai\India resolves to MAA – maa-efz.ms-acdc.office.com
If user using WIFI, ask the user to switch to LAN and check the performance issues still exists, just to isolate the issue not with WIFI.
Check the Outlook Connectivity Status
To identify the network latency, Open outlook in normal mode and check the connection status by Ctrl + Right click the Outlook icon from system tray and select connection status.
On the Connection Status, Connections with larger request count is for Synchronizing mailbox. On the above image, the Average Response Time is 131 ms & Average Processing Time is 4 ms. Network Round Trip Time calculate as 127ms (Avg Resp – Avg Proc)
Ensure the values are below to confirm no issues with Proxy or Network.
- Max Avg Proc Time (Exchange RPC Latency) = 25ms
- Max Network RTT Time (Network Ping Time) = 500ms
- Max Avg Resp Time (Exchange RPC Latency + Network Latency) = 525ms
If, Network RTT above 500ms involve Network Team and If Avg Proc time is above 25ms then issue with Office 365, raise a ticket with Microsoft.
On the Req/Fail column, high fail count shows a network disconnection. Involve network team to identify the network connectivity problem. .
If the network and Exchange connection are good and still an Outlook performance issues, check the CPU / Memory / Disk Utilization are not above 80 % consistently. Sort the CPU /Memory / Disk one by one in ascending order and see if any unwanted applications closed and reopened when required.
If Antivirus constantly utilize the resources then involve relevant team to identify whether it is normal. If it is not expected, ask the respective team to troubleshoot.
Try to differentiate whether it is an Outlook performance problem or System Performance issue causing the outlook slowness. If a System Performance Issue identified outlook performance degradation is expected.
Check the Outlook Add-Ins
If the CPU usage is high and outlook is consuming more CPU, then Add-Ins may cause the problem. Disable all the Outlook Add-In (MacAfee, WebEx & Report Spam) or Open Outlook in safe mode and check any changes to Outlook performance. If Performance improved, then one of the add-in caused a performance problem. Try to disable add-in one by one to isolate the problem and report the Add-In owner.
Outlook -> File -> Info -> Manage COM Add-Ins
Ensure User is maintaining the below which will prevent outlook slowness
- 100, 000 items per folder
- 5,000 items per calendar
- 500 folders in mailbox
Check whether OST is fragmented >1000 frags/file
OST Files considerations
Large OST files impacts the system performance, ensure to keep the OST files larger than 10 GB on a SSD disk.
If not using SSD, ask the outlook Sync slider to keep the OST files less than 10 GB. Make a note, when user changes the sync slider, outlook will synchronize the emails as per the settings and user has to wait until the sync completes.
Check the Disk capability
OST size above 5 GB size has to be placed in a fast disk to get good performance result. WinSAT Windows System Assessment Tool can help to analyze the disk read write capabilities. Run the below command on an administrative command prompt and check the Disk Random Writes value.
Disk Random Write value less than 15 MB/s can provide good performance only for OST of less than 5 GB size.
One of the important thing to look at is the Anti-Virus scanning exclusions. Applications like Outlook.exe, Lync.exe and in addition, the files associated with that are to be excluded from Virus scanning.