CCleaner is not a registry cleaner. it has a registry cleanup component, but it's main purpose has always been disk cleanup.
Having a larger registry doesn't slow down access time any more then having a lot of files on a disk. recall the heirarchal ordering. If you have a folder on C: with thousands of files, it's not going to slow down accesses across the drive. In fact, it won't even slow down accesses within that folder.
The registry is a database. Yes. One might gather this from the fact that it's full name is "registration database".
However.
A Larger database does not affect access to records within that database, additionally, I might point out that databases like Jet, Access, MySQL, SQL Server, Oracle, etc. are relational databases- not heirarchal. Strictly speaking there is one "flat" set of tables containing records; heirarchy is hacked in via lookup Ids into other tables.
http://www.sentinelchicken.com/research/registry_format/The registration database, however, is fully hierarchal. Many people make the assumption that accessing a key involves accessing the keys before it in the list- or at least "seeking" past them.
While disk wise this is true, the registry stores key and value record offsets in the parent key's records. The value or key records of the parent key will need to be enumerated, but considering the fact that even a PC from 1998 could iterate over nearly 100 thousand a second it's not going to contribute to slowdown unless you have that many, and that simply never happens. (I am speaking of values and subkeys of a single key, not the registry as a whole). And even then, I imagine they employ a number of other methods aside from the basic sequential access to each record, such as hash maps.
Access to the leaves (values) of the registration database tree follow the very same rules as accessing the leaves in a Tree structure; the speed is O(n), where n is the number of nodes that need to be passed through. Unless you have a registry key that is nested beneath hundreds of subkeys that simply isn't going to be a problem.
If that were the case, why would Piriform spend so much time & effort developing one for free?
I'm sorry, is this an actual argument or a joke?
"Somebody did it so it's a good idea" is hardly grounds for a dismissive attitude on the subject. Bad ideas are acted on all the time, just because a bad idea is acted on doesn't suddenly make it a good idea. Additionally, CCleaner is <NOT> a registry cleaner. it provides some basic housekeeping tasks (half of which are useless, I'll get into those in a moment) but it does not make any claims that it "cleans" the registry.
As for the various registry "integrity" checks it can perform:
"SharedDLLs" have not been used by the EXE loader since windows 98. In fact the only thing that accesses them in common practice is the installer that writes the value there. Safe to delete, but all you gain is a few extra bytes of disk space.
"Unused file extensions"
This is absolutely meaningless. It's like scanning your drive for empty folders. would you expect deleting empty folders on your drive to speed things up? No. This doesn't speed registry access up either. No speed is gained from this either even with files with that extension- windows would try to find the section to determine wether it exists anyway.
"ActiveX and Class issues"
This is the only meaningful and productive thing you can check for. The best part is almost nobody knows what it's scanning for. I won't even BOTHER to reiterate the same thing I've spoken of in the dozen other far too long posts on this subject I've made. This is only useful in that it prevents applications from trying to instantiate an object only to find that the DLL or executable that is registered is not found.
"type libraries"
pretty much the same as above.
"Application paths"
This found 10 issues on my machine.
But all the files it reported as missing were present. More on that in a moment.
'Help files"
another meaningless key. you save a few bytes, maybe, if it discovers that helpfiles registered here don't exist.
"installer files"
This might be sensible... usually. more on that in a moment as well.
"Obsolete software key"
Again, meaningless. no harm, but no real gain.
And also- an far larger problem.
CCleaner's registry checker thing can actually <corrupt> your registry on Vista and 7.
If you don't run it as admin, you can pretty much guarantee some issues in the future. Consider for a moment that a program requires administrator privileges to access files in the system folders or program files folders.
Now, that's sensible.
However, when CCleaner tries to access a file in program files to check if it exists based on the value of a key (say, in Application paths) It get's back access denied and assumes it doesn't exist, thus marking the key bad. this happens with <All> the various scans; such as installer scans (which are usually stored in the windows folder).
So if you forget to run it as admin you're deleting keys that <aren't> obsolete, disassociating files from programs that <DO> exist.... creating problems,
where there are none.
I still don't understand why a software developer would provide something that people want, if he can't make any money from it.
No offense intended, Quantos, but that is the most ignorant thing I've ever read. It's not always about money. Why do painters paint? why did Michelangelo sculpt David? was it because he could get money for it? Probably not. I don't even think he did, actually.
The only people that didn't understand famous artists during their time were exactly that way- they only cared about the bottom line, and couldn't imagine anybody else thinking differently, they couldn't leave their own little world of shekels and talents and actually appreciate what was around them. Sure- they contributed to the community, at a price.
However- are there any famous money-lenders? are there any famous Investment bankers? Do they have busts of loan-sharks in museums? Are their memorials to great financiers in the same token as those in the U.S for the many people who shaped that country? No. the possession and seeking of material goods is a sign of vanity that almost precludes any of these types of people from ever being considered for recognition, except perhaps in the form of infamy.