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
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
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).