AEM_performance Analysis from top to Bottom for each layers of the system

Reference Links

Step	Title	Resources
Step 0	Analyze Request Flow	You can use standard HTTP request analysis in the browser to analyze the request flow. For more info on how to do this on Chrome, see: https://developers.google.com/web/tools/chrome-devtools/profile/network-performance/resource-loading https://developers.google.com/web/tools/chrome-devtools/profile/network-performance/understanding-resource-timing
Step 2	Are requests coming from external hosts?	You can use standard HTTP request analysis in the browser to analyze the request flow. See the above links on how to do this on Chrome.
Step 3	Can the requests be cached?	For more information on cacheable requests and general Dispatcher performance optimization advice, see Dispatcher Performance Optimization.
Step 4	Are requests coming from the Dispatcher?	Check the Dispatcher debugging documentation to see if the requests are cached properly.
Step 5	Is the Dispatcher trying to authenticate each request via AEM?	Check if the dispatcher sends HEAD requests to AEM for authentication before delivering the cached resource. You can do this by looking for HEAD requests in the AEM access.log. For more information, see Logging.
Step 6	Is the geographic location of the Dispatcher far away from the users?	Move the Dispatcher closer to the users.
Step 7	Is the network layer of the Dispatcher OK?	Investigate the network layer for saturation and latency issues.
Step 8	Is the slowness reproducible with a local instance?	Use Tough Day to replicate "real world" conditions from the production instances. If this is not realistic for the slace of your development, make sure to test the production instance (or an identical staging one) in a different network context.
Step 9	Is the geographical location of the server far away from the users?	Move the server closer to the users.
Steps 10 and 29	Investigate network layer	Investigate the network layer for saturation and latency issues. For the author tier, it is recommended that the latency does not surpass 100 milliseconds. For more information on performance optimization tips, see this page.
Step 11	Move server closer or add one per region
Step 12	Troubleshoot AEM server	Check the following sub steps in the diagram for more information.
Step 13	Check hardware requirements	Check the documentation on Hardware Sizing Guidelines.
Step 14	Check for frequent causes of performance issues
Step 15	Find slow requests	You can check for slow requests by analysing the request.log or by using rlog.jar. For more information about using rlog.jar, see this page. See Using rlog.jar to find requests with long duration times.
Step 16	Profile server	For information about profiling tools you can use with AEM, see Tools for Monitoring and Analyzing Performance.
Step 17	Find slow methods in profiling
Step 18	Common scenarios of profiling	See Analyzing Specific Scenarios in the Performance Optimization section.
Step 19	100% CPU	https://helpx.adobe.com/experience-manager/6-3/sites/deploying/using/monitoring-and-maintaining.html#MonitoringPerformance
Step 20	Out of memory	Out Of Memory My application throws out-of-memory errors Analyze Memory Problems on Helpx.
Step 21	Disk I/O	See the Disk I/O section in the Monitoring and Maintaining documentation.
Steps 22 and 22.1	Cache ratio	See Calculating the Dispatcher Cache Ratio.
Step 23	Slow queries	Best Practices for Queries and Indexing
Step 24	Repository tuning	Performance Tuning Tips Configuring for Performance Repository Performance Tuning
Step 25	Workflows running	Concurrent Workflow Processing Configure the Queue for a Specific Workflow Regular Purging of Workflow Instances Transient Workflows
Step 26	MSM Infrastructure	Multi Site Manager Best Practices
Step 27	Assets tuning	Assets Synchronization Service Multiple DAM Instances Performance tuning tips articles here and here.
Step 28	Unclosed sessions	Checking for unclosed JCR sessions
Step 30	Move dispatcher closer (add one per "region"?)
Step 31	Use CDN in front of dispatcher	Using Dispatcher with a CDN
Step 32	Use session management at the dispatcher level to offload AEM server	Enabling Secure Sessions
Step 33	Make requests cacheable	General Dispatcher Configuration Configuring the Dispatcher Cache How to improve cache ratio; make requests cache-able (Dispatcher best practices) Also, take into consideration the below settings in order to optimize your caching configurations Set a no-cache rule for HTTP requesrst that are not GET Configure query strings to not be cacheable Do not cache URLs with missing extensions Cache authentication headers (possible since Dispatcher version 4.1.10)
Step 34	Upgrade dispatcher version	You can download the latest Dispatcher version at this location: https://www.adobeaemcloud.com/content/companies/public/adobe/dispatcher/dispatcher.html
Step 35	Configure dispatcher	Configuring the Dispatcher
Step 36	Check cache invalidation	Cache Invalidation for the Author tier; Cache Invalidation for the Publish tier.
Steps 37 and 38	Lazy-loading	See the Gem Session on AEM Web Performance.
Step 39	Use pre-connect to reduce connection overhead	See the Gem Session indicated above. Also, additional documentation preconnect on W3c:https://www.w3.org/TR/resource-hints/#dfn-preconnect
Steps 40 and 41	External hosts latency and response time	Investigate the latency and response time for the external hosts.
Steps 45 and 47	Using HTTP/2	See the Gem Session for steps 37,38 and 39. Also, check out this forum post on HTTP/2 support.
Step 49	Shrink payload size	Enable Gzip and shrink the image size.
Steps 42 and 43	Keep-Alive	Is the Keep-Alive header present in the different requests to re-use connections? Otherwise, it would mean that each requests leads to another connection establishment, which introduces unnecessary overhead. (Standard HTTP request analysis in the browser) You can check the Proxy Server tool to check for Keep-Alive connections.
Step 44	How many requests are made?	Perform standard HTTP request analysis in the browser.
Step 46	Reduce number of requests	Concatenate resources (images, CSS sprites, JSON, etc.) Clientlibs embedding: Creating Client Library Folders - see heading Using embedding to minimize requests
Step 48	What is the size of the payload?	Standard HTTP request analysis in the browser
Steps 50 and 51	JS code blocking	https://docs.adobe.com/ddc/en/gems/aem-web-performance.html