cpu spike after upgrade from tomcat 6.0.36 to tomcat 7.0.57

[musafir]

Hello, ugraded tomcat from 6.0.36(jdk 6) to tomcat7.0.57  (jdk7)..
os:centos 6.6 ...seeing high cpu spike after upgrade.... doing top
and  thread dump shows  only thread that is always using cpu is:
 "ContainerBackgroundProcessor[StandardEngine[Catalina]]" daemon
prio=10 tid=0x00007ff8fc599800 nid=0xc1d2e waiting on condition
[0x00007ff803ffe000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at 
org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1513)
        at java.lang.Thread.run(Thread.java:745)

disabled  backgroundProcessorDelay (backgroundProcessorDelay=-1)
..don't see any thread that is always using cpu..

Q: why backgroundProcessorDelay will cause cpu spike. Is this disabled
in tomcat6 by default?
Q: will  disabling backgroundProcessorDelay cause any other
performance issues with tomcat7.


Thanks for Help!!

Regards