The SAP slow performance can be affected by one or all of the followings bottleneck. It is very hard to pin point which is main cause however usually are combined effects that needs to determine by isolation.


In general, below are the starting point to investigate slow performance issue:

1) Slow when logon or logout of SAP?

2) Slow when open SAP Module, is that all module or just one module, which module?
4) Slow when loading SAP data. Is that all window or just one window, which window?
5) Slow when input data in SAP. Is that all function or just one function, which function?
6) Slow when saving data in SAP. Is that all function or just one function, which function?

7) Slow when running SAP Report, is that all reports or one report, which report ?

8) Slow when working on SAP Addon, which Addon?


System stability can be isolated with below step-by-step isolation.

1) Network connectivity and/or issue
2) Database Server permission and/or connection issue
3) SAP Server SLD connection issue
4) Windows domain user permission issue
5) Local PC hardware issue
6) Local PC Operating System Issue
7) Local PC Windows folder permission issue
8) Local PC database driver issue
9) Local PC SAP DI-API issue

10) Local PC SAP user issue

11) Local PC SAP standard application issue
12) Local PC SAP custom addon application issue


Below are just recommendations to explore possible bottleneck, it is not a solution to resolve performance issue. Please work with your system and network engineer to review and resolve.


Best practice to compare the performance of SAP Application runs at the SAP Server against the Client’s PC. Isolate root cause and make necessary fine-tuning and adjustments at Network, Server or Client PC.


Source
Symptoms
Possible cause of slow performance 
Network Bandwidth
Users are experiencing different speed at different time, printing is slower or faster depends on the time of the day
L.A.N. network traffic and Internet network traffic.
Eg. Slow when the business day starts when everyone login to emails, or sending big files via internet at certain time. Distance and quality of the L.A.N cable may sometime affecting the performance as the longer is the cable, the signal is weaker

W.A.N. network may be affected by Telco internet speed and routing through different hubs etc.
Terminal Server
Users are experience slow response on screen or freezing
Terminate sessions are heavily rely on L.A.N or internet bandwidth and SAP is sensitive to network stability. Any trip (sudden pause) in network will cause application to freeze and return after several seconds, or sometime may just crash return with License Server or SLD not found.
Overloading of terminal sessions or congested network may cause user to experience delay response, eg. typing is faster than display

Terminal Server Resources allocation distributing the right amount of RAM and CPU power to each users. Unattended ‘Disconnected’ Terminal Session may cause slow performance to other users
SQL Server
User are experiencing delay in adding or updating records, or returning results from a query or report
Configuration of SQL server to handle multiple SQL sessions, complex queries and SQL Agent Jobs.

Speed of harddisk, drive mappings, RAM and CPU allocation behaviour will have impact of SQL Server performance. Review SQL Server configuration to match with required performance.

Review the number, type of Processors and clock speed,
Review the type of Harddisk and speed.
Review the type of RAM and speed.

PC/Operating System
Different users experiencing different speed at different PC
PC Hardware, RAM, CPU and Operating System specification.

Review the CPU, Harddisk and RAM Speed.
Review the type of network card and speed.
Review whether PC is connect through L.A.N cable or WIFI.
Windows Applications
Different users experiencing different SAP behaviour in different PC
Other Windows Applications, SAP or SAP Addon is causing the SAP Business One Core application to work with poor performance. Possible of client application issues, windows permission/Domain User Profile, Windows Update etc.
Antivirus/Virus
Users are experiencing application pause or unusual behaviours
Antivirus is actively scanning each file or memory processed at Client PC, though most cases SAP program folders are excluded.

When PC is affected by virus and starts spreading itself exploring files to corrupt