What indexing service do is to catalog each and every file present in you hdd. when you search for a file windows search for it in this catalog thus giving you lightning fast results (rather than searching it in the Hdd).but it has some drawbacks (depends on user to user
), will cause overhead as it has to catalog everything thus makig pc a bit slow.
and enabling "Indexing Service" Option in Every Drive alone wont do it, one must have "Indexing Service" enabled( from services.msc) and running for it to serve its purpose.
if you have tons of tons of tons of tons of tons of tons of files in your hdd which needs to be searched on regular basis, then use this usefull feature
if u are not a search maniac then you can safely turn the indexing service off( from services.msc).