Why is my Macbook pro now extremely slow and not running things like powerpoint any more?

Question

I'm sure I'm not the only one.
Mavericks installed. Now my Macbook Pro is slower than a one-legged tortoise.
It won't run powerpoint, which just crashes. en my keyboard misses the first part of sentences because it can't keep up. I have to double check everything I type. I'm trying to run a business, and I'm losing time, money and the will to live.
I cannot reinstall microsoft office, as I bought my macbook Pro (2 GHz Intel Core i7, 8GB 1600 MHz DDR3) from a seller who cleanly installed Mountain lion for me, and installed Office 11 on it. I do not have any installation disks. I have been forced to downgrade to Mountain Lion, which I'm still waiting for Apple to send to me.
Is there anyone out there who can give me any help. I'm not paying Apple any more money. Why should I? I've already been forced to rebuy an operating system that my Macbook previously had installed. 
Not only that, I think I have an expanding battery issue, and my trackpad is now broken. Just to add to my woes.
Has anyone had a solution to solving the Mavericks debacle?
Please somebody, help.
Please.
Before I start self harming.

Answer 1

Hi all;
I agree with stobston,  many thanks to cbs20 for your inputs.  I was stuck with this one also.   I'm a former UNIX sysadmin; thanks so much for pointer to etrecheck.  It's nice to be able to look under the hood.
I had the same problem, Powerpoint was so slow as to be nearly useless.  Apparently different cause&effect from stobston's case.  Here's what worked for me.  Sorry if I'm stating the obvious below; I'm new to MacOS after many years on MS-Windows;
First, I ran etrecheck and got the following;
Hardware Information:
         MacBook Air (13-inch, Mid 2013)
         MacBook Air - model: MacBookAir6,2
         1 1.3 GHz Intel Core i5 CPU: 2 cores
         4 GB RAM
Video Information:
         Intel HD Graphics 5000 - VRAM: 1024 MB
System Software:
         OS X 10.8.5 (12F45) - Uptime: 0 days 2:59:30
Disk Information:
         APPLE SSD SM0256F disk0 : (251 GB)
                   disk0s1 (disk0s1) <not mounted>: 209.7 MB
              Macintosh HD (disk0s2) / [Startup]: 250.14 GB (150.98 GB free)
                   Recovery HD (disk0s3) <not mounted>: 650 MB
USB Information:
         Apple Internal Memory Card Reader
         Apple Inc. BRCM20702 Hub
                   Apple Inc. Bluetooth USB Host Controller
         Logitech USB Receiver
Thunderbolt Information:
         Apple Inc. thunderbolt_bus
Gatekeeper:
         Anywhere
Launch Daemons:
       [loaded]             com.adobe.fpsaud.plist Support
       [loaded]             com.microsoft.office.licensing.helper.plist Support
Launch Agents:
       [loaded]             com.citrix.AuthManager_Mac.plist Support
       [running]             com.citrix.ReceiverHelper.plist Support
       [running]             com.citrix.ServiceRecords.plist Support
User Launch Agents:
       [loaded]             com.citrixonline.GoToMeeting.G2MUpdate.plist Support
       [loaded]             com.google.keystone.agent.plist Support
User Login Items:
         iTunesHelper
         Dropbox
         Google Drive
Internet Plug-ins:
         FlashPlayer-10.6: Version: 13.0.0.206 - SDK 10.6 Support
         QuickTime Plugin: Version: 7.7.1
         Flash Player: Version: 13.0.0.206 - SDK 10.6 Support
         CitrixICAClientPlugIn: Version: 11.8.2 - SDK 10.7 Support
         SharePointBrowserPlugin: Version: 14.3.8 - SDK 10.6 Support
         Silverlight: Version: 5.1.30214.0 - SDK 10.6 Support
         JavaAppletPlugin: Version: 14.9.0 - SDK 10.7 Check version
Audio Plug-ins:
         AirPlay: Version: 1.7 - SDK 10.8
         iSightAudio: Version: 7.7.1 - SDK 10.8
iTunes Plug-ins:
         Quartz Composer Visualizer: Version: 1.4 - SDK 10.8
User Internet Plug-ins:
         CitrixOnlineWebDeploymentPlugin: Version: 1.0.105 Support
         WebEx64: Version: 1.0 - SDK 10.6 Support
         ZoomUsPlugIn: Version: 2.0.31405.1104 - SDK 10.8 Support
3rd Party Preference Panes:
         Flash Player  Support
Time Machine:
         Time Machine not configured!
Top Processes by CPU:
            3%         WindowServer
            1%         fontd
            1%         Microsoft PowerPoint
            1%         Microsoft Word
            0%         coreservicesd
Top Processes by Memory:
       254 MB     Microsoft PowerPoint
       225 MB     WebProcess
       135 MB     mds
       135 MB     Microsoft Excel
       131 MB     Finder
Virtual Memory Information:
       891 MB     Free RAM
       1.68 GB     Active RAM
       833 MB     Inactive RAM
       524 MB     Wired RAM
       1.52 GB     Page-ins
       0 B              Page-outs
Note that I had no heavy CPU processes like stobston had.  There are some processes using lots of memory  though.  Made me wonder, could it be  a swap or contention issue?  I have a Macbook Air, so 'swapping' doesn't mean what it used to mean.  Anyway, I tried closing Excel and Finder.  Powerpoint was still slow.   I ran etrechek again.  WebProcess and mds are still running at the same memory usage; nearly half a gig between them.  WebProcess is Safari; shutting down Safari didn't help.   I have heard that Safari has had memory leaks, I don't know if that's true or not.  mds is the MetaData Server for SpotLight. I had run Spotlight several times today, and also did a lot of desktop cleanup.   That might have triggered mds.
I don't know how well Mountain Lion reclaims memory ( now I'm really getting into the weeds ), so I shut down  MacOS  and restarted it.  This time, I started up PowerPoint first, with nothing else running.  Problem solved.  PPT is running fine.
Thanks again all for your inputs.  An hour ago, I had no idea where to start.