In SAP systems, there are several transaction codes (Tcodes) and tools available to check and analyze system slowness. Here are some commonly used ones:

1. ST03/ST03N: These Tcodes provide workload and performance statistics for SAP systems. You can analyze system performance, identify top transactions, and check response times.
2. STAD: This Tcode allows you to analyze the workload of the SAP system and provides detailed statistics on user activities, executed transactions, and response times.
3. SM50/SM66: These Tcodes display the process overview and can help identify any long-running or stuck processes that might be causing system slowness.
4. ST05: This Tcode is used for SQL trace and can help analyze the performance of database calls made by SAP transactions. It allows you to identify slow-performing database queries.
5. SE30: This Tcode is used for runtime analysis and can help identify performance bottlenecks in ABAP programs. It provides detailed information about the execution time of each statement and subroutine.
6. SM21: This Tcode displays the system log and can help identify any system-related errors or issues that might be causing performance problems.
7. SAP Solution Manager: It provides a range of tools for monitoring and analyzing system performance, including End-to-End Root Cause Analysis (RCA) and Performance Monitoring Dashboards.
8. SAP EarlyWatch Alert: It is a proactive monitoring service provided by SAP that analyzes system performance, identifies potential issues, and provides recommendations for performance improvements.
9. SAP Performance Optimization Workload Analyzer (PWA): It is a powerful tool for analyzing workload and performance data. It helps identify performance bottlenecks, provides optimization recommendations, and supports capacity planning.