I am currently using Mac OS X Lion 10.7.4 in my MacBook Pro. Until yesterday it was working very nice. Today I found my system is slow. A quick look with ps -ef command revealed that spotlight indexing is continuously working and making my system slow. I realized that Spotlight kept indexing for hours and my system is getting dead slow. So with few little commands I found a very quick solution to fix this spotlight indexing issues
Open your terminal command line (Applications/Utilities) and type the following command
sudo rm -rf /.Spotlight-V100/*
Now with this command spotlight indexation will stop and it will delete your current corrupted spotlight index database.
STEP 2. Start again Spotlight index
Now type and execute the second command given below to start re-index of Spotlight.
sudo mdutil -i on -E /
Wait for sometime and Spotlight should start indexing your system within few minutes.
After using the above commands my system is now working fine.