CPU usage becomes high when using the search feature in the Package Manager UI (/crx/packmgr/index.jsp).
For example, when you input "content" in search field, the following GET request with "q=content" parameter is sent.
30/May/2017:17:37:05 +0900  -> GET /crx/packmgr/list.jsp?_dc=1496133424888&_charset_=utf-8&includeVersions=true&q=content HTTP/1.1
The traversal warning below would show in the error.log:
31.05.2017 09:20:06.569 *WARN* [qtp1943664859-1656471] org.apache.jackrabbit.oak.spi.query.Cursors$TraversingCursor Traversed 7000 nodes with filter Filter(query=select b.[jcr:path] as [jcr:path], b.[jcr:score] as [jcr:score], b.* from [nt:file] as a inner join [nt:base] as b on isdescendantnode(b, a) where isdescendantnode(a, '/etc/packages') and contains(b.*, 'content') /* xpath: /jcr:root/etc/packages//element(*, nt:file)//*[jcr:contains(., 'content')] */, path=/etc/packages//*); consider creating an index or changing the query
AEM 6.1 SP1 and SP2
Avoid using this feature in versions prior to AEM 6.2.
This issue was fixed on AEM6.2 and later versions and a fix has been back-ported to AEM 6.1 SP2 CFP13 (and later 6.1 CFPs).