Here are some test results: Laptop: Intel Core i7-6820HQ CPU 2.70GHz × 8 16 o RAMsettings as per https://github.com/keycloak/keycloak/blob/3.4.1.CR1/testsuite/perform..., KC and postgres are on the same laptop. Scenario: /users call with username criteria returning a 100 users page.1000 total users in db. Before optimization: 1 thread, no wait tx/s: 9 avg response time (ms): 110 CPU: java=80%, postgres=20% mem 5 thread, no wait tx/s: 31 avg response time (ms): 149 CPU: java=628%, postgres=135% (19 processes with 7.6%) mem: 1g used 10 thread, no wait tx/s: 41.5 avg response time (ms): 219 CPU: java=613%, postgres=135% (9 processes with 15%) mem: 400m used <note: same tx/s for 20threads) After optimization 1 thread, no wait tx/s: 132 avg response time (ms): 7 CPU: java=85%, postgres=13% mem 250m 5 thread, no wait tx/s: 365 avg response time (ms): 13 CPU: java=440%, postgres=40% mem: 1g used 10 thread, no wait tx/s: 385 avg response time (ms): 25 CPU: java=600%, postgres=54% mem: 1Go used 20 thread, no wait tx/s: 450 avg response time (ms): 42 CPU: java=600%, postgres=57% mem: 1.2Go used <note: same tx/s for 30threads) Cheers,Adrian Le lundi 12 février 2018 à 22:56:22 UTC+1, Adrian Gonzalez <adr_gonzalez(a)yahoo.fr&gt; a écrit : As a workaround for issue 2, we can activate Permissions in realm-management Client (I've created a custom realm to avoid working on master realm).This way, we ensure root.realmResourceServer() is not null.But that's a bit convoluted :(   Le lundi 12 février 2018 à 22:37:08 UTC+1, Adrian Gonzalez <adr_gonzalez(a)yahoo.fr&gt; a écrit : Hello, I'm testing KC 3.4.3 REST API and I get n+1 selects (aka 701 selects when asking for a page of 100 users). Issue 1:Looking at the code, there's n+1 select on the following fields UserEntity: - attributes- requiredActions- credentials 7The n+1 select is triggered by https://github.com/keycloak/keycloak/blob/8e53ccf5abb4d7cc3ab8d5abc9d0... This can be solved by annotated these attributes with (a)Fetch(FetchMode.SUBSELECT).I also tried using EntityGraph, but it doesn't work since we're using Collection types (instead of Set) and because we're doing pagination while fetching ToMany associations. Issue 2: n+1 select because we don't cache null values We have this select executed n times:select    resourcese0_.ID as ID1_60_0_,    resourcese0_.ALLOW_RS_REMOTE_MGMT as ALLOW_RS2_60_0_,    resourcese0_.POLICY_ENFORCE_MODE as POLICY_E3_60_0_ from    RESOURCE_SERVER resourcese0_ where    resourcese0_.ID=? This one is done here:https://github.com/keycloak/keycloak/blob/8e53ccf5abb4d7cc3ab8d5abc9... In default setup,root.realmResourceServer() is null.Since StoreFactoryCacheSession doesn't cache null values, the return value never gets cached.I don't know how to easily solve that one. Should I create an issue ? Thanks 

Hello, I created the following JIRA issue :https://issues.jboss.org/browse/KEYCLOAK-6589 And  I sent a PR to fix the issue on the User search API : https://github.com/keycloak/keycloak/pull/4999 Could a KC committer please consider it ? Thanks,Adrian Le mardi 13 février 2018 à 01:04:01 UTC+1, Adrian Gonzalez <adr_gonzalez(a)yahoo.fr&gt; a écrit : On Group API, I think it's less critical, first loading is resource consuming, but afterwards, the groups are in cache. With a db with 1000 groups (no hierarchy) 1. The first call to /groups with first=0, max=100 issues 3076 SQL statements.If I add @Fetch(Subselect), the number of statements is reduced to 2077 (2 times n+1 select, n being 1000).Then the rest is done in https://github.com/keycloak/keycloak/blob/a743600b344763ce2e7f70a625f5... 2. later calls are cached, so no more db access (until a group is updated.removed I assume) Le mardi 13 février 2018 à 00:26:21 UTC+1, Adrian Gonzalez <adr_gonzalez(a)yahoo.fr&gt; a écrit : Here are some test results: Laptop: Intel Core i7-6820HQ CPU 2.70GHz × 8 16 o RAMsettings as per https://github.com/keycloak/keycloak/blob/3.4.1.CR1/testsuite/perform..., KC and postgres are on the same laptop. Scenario: /users call with username criteria returning a 100 users page.1000 total users in db. Before optimization: 1 thread, no wait tx/s: 9 avg response time (ms): 110 CPU: java=80%, postgres=20% mem 5 thread, no wait tx/s: 31 avg response time (ms): 149 CPU: java=628%, postgres=135% (19 processes with 7.6%) mem: 1g used 10 thread, no wait tx/s: 41.5 avg response time (ms): 219 CPU: java=613%, postgres=135% (9 processes with 15%) mem: 400m used <note: same tx/s for 20threads) After optimization 1 thread, no wait tx/s: 132 avg response time (ms): 7 CPU: java=85%, postgres=13% mem 250m 5 thread, no wait tx/s: 365 avg response time (ms): 13 CPU: java=440%, postgres=40% mem: 1g used 10 thread, no wait tx/s: 385 avg response time (ms): 25 CPU: java=600%, postgres=54% mem: 1Go used 20 thread, no wait tx/s: 450 avg response time (ms): 42 CPU: java=600%, postgres=57% mem: 1.2Go used <note: same tx/s for 30threads) Cheers,Adrian Le lundi 12 février 2018 à 22:56:22 UTC+1, Adrian Gonzalez <adr_gonzalez(a)yahoo.fr&gt; a écrit : As a workaround for issue 2, we can activate Permissions in realm-management Client (I've created a custom realm to avoid working on master realm).This way, we ensure root.realmResourceServer() is not null.But that's a bit convoluted :(   Le lundi 12 février 2018 à 22:37:08 UTC+1, Adrian Gonzalez <adr_gonzalez(a)yahoo.fr&gt; a écrit : Hello, I'm testing KC 3.4.3 REST API and I get n+1 selects (aka 701 selects when asking for a page of 100 users). Issue 1:Looking at the code, there's n+1 select on the following fields UserEntity: - attributes- requiredActions- credentials 7The n+1 select is triggered by https://github.com/keycloak/keycloak/blob/8e53ccf5abb4d7cc3ab8d5abc9d0... This can be solved by annotated these attributes with (a)Fetch(FetchMode.SUBSELECT).I also tried using EntityGraph, but it doesn't work since we're using Collection types (instead of Set) and because we're doing pagination while fetching ToMany associations. Issue 2: n+1 select because we don't cache null values We have this select executed n times:select    resourcese0_.ID as ID1_60_0_,    resourcese0_.ALLOW_RS_REMOTE_MGMT as ALLOW_RS2_60_0_,    resourcese0_.POLICY_ENFORCE_MODE as POLICY_E3_60_0_ from    RESOURCE_SERVER resourcese0_ where    resourcese0_.ID=? This one is done here:https://github.com/keycloak/keycloak/blob/8e53ccf5abb4d7cc3ab8d5abc9... In default setup,root.realmResourceServer() is null.Since StoreFactoryCacheSession doesn't cache null values, the return value never gets cached.I don't know how to easily solve that one. Should I create an issue ? Thanks