As much as we'd all like to have cutting-edge hardware and equipment for our favorite hobbies, often we have to make do with what we have. Right now I'm using a first-gen Macbook that will be celebrating it's fourth birthday soon. It's still running great, even if it sometimes has some problems with raiding. I have researched and spent a lot of time getting my UI/hardware to work as well as possible even on a "casual" computer. Here are the things I did to make those chaotic fights bearable, and even playable.
Be Honest About Addons
We're healers and we love addons, right? (I love addons - not just because I'm a healer but I like having a customized UI). There's lots of recommended goodies for us to do our jobs, but some of these can bog a computer down. It takes some self-honesty to pare down to just the ones you need - I ended up saying farewell to some addons that were nice for when I wasn't raiding, but hurt me too much when I was.
1. Goodbye, Recount. If phases with adds turn your computer into a 3 FPS mess until the adds disappear and 2 of your DPS are dead, then recount has got to go. I was sad to turn it off, but I'm lucky I still have access to those fights because Mayhem runs it. Damage meters can be helpful to assess performance and learn about what happened in a fight, but during large-scale fights it's information overload for a computer. If you still want log assessment, consider if your guild does a WoL or if you could get one of the officers to start posting your guild's WoL logs for you to peruse. Life in Group 5 just did a great post for analyzing WoL. Check out the memory footprint of your addons (mouseover the game menu icon, it will be on the tooltip), and keep an eye on addons that use more than a couple of megs usage. Consider purging anything that isn't raiding related for your raiding nights. Auctioneer should go on a bank alt, and you can re-enable Questhelper after the raid disbands. Go back to your addons selection screen and take a long, hard look at what you find there. Do I really need this addon to raid?
2. Hello, Quartz. Quartz has been a must-have addon for me because of the latency timer. It's a lot easier to plan your casts with this addon and it doesn't have a large memory footprint.
3. Consolidate. Do you have three and four addons that all have overlapping functionality? The Beacon of Light Timer is a great addon, but do you need that if you're running Healbot which as it's own built-in countdown for that and Sacred Shield? Do you need Decursive if you're running Vuhdo? My small screen and low processing power mean I'm looking for the simplest way to show me information. I don't need it displayed twice so long as I'm looking for it in the right place right away. I have been using Pitbull4 (in my experience, the raid frames that bogged down my computer the least), but I've been contemplating if I need to use a raid frames mod at all since Healbot has been rock-solid for months, even through patches.
4. Macros. Macros don't take memory to use, while addons do because they are constantly running. If there are addons you could pare down and replace with macros and keybindings, consider it. I don't use any addons like this that I can think of, but I know I've seen them before. I don't need a mod that keeps track of my trinket cooldowns because I have my on-use trinkets macro'd to my mouseover healing. It may take some research but if you haven't learned how to use macros yet, I would recommend it. WoWWiki has a page dedicated to usefu macros to get a novice started.
The long and short of it is - run the least amount of addons you can manage, and experiment to find the best-performing UI that still delivers the information you need.
Take care of Hardware
There are lots of sites on the internet that can give you solid advice for keeping your computer in good shape. Macworld has a great page about maintenance (I am frequently guilty of going weeks without relaunching, so there's still more I can be doing for my equipment). Apple's website has also has their suggested maintenance.
For all the Windows users out there, there's even more resources for you. Fulltimewow did a post on squeezing the most out of WoW performance. The post is a bit older but the information is still solid. His Wow Forums performance link is broken, I found the 3.x version here. Windows.com will have a maintenance page for most of their OS's for all of the nitty-gritty stuff you can do to keep your computer running smoothly outside of Wow.
The official WoW forums have lengthy posts for both Mac and Windows users. It's the best information I could offer to anyone. If you are serious about making sure your computer is up to par, it will take some time to get knowledgeable, and then start tweaking your settings. It's been worth it for me.
A Small Upgrade Can Be Big
Even if you can't get gaming quality hardware in your computer, check how much RAM your system is running. This is the one upgrade that can make a huge difference, especially for the price. WoW recommends 1 gig of RAM but when Wrath came out I started having performance problems when I was grouped or in a town just running the minimum spec. The guys at Best Buy will be happy to tell you that more RAM is always better (and that you should buy it, right now), however, your system will also have a cap on how much extra RAM can be shoved inside. For my older Macbook, the limit is two gigs. If you are running with only 1 gig of RAM, you will love how World of Warcraft will perform with 2 gigs, and RAM is quite affordable.
It's really no fun to turn all your settings down to the bare minimum, but for an older computer or even a computer that's not built for gaming, it might be necessary. I have just about everything turned to the absolute minimum, however, be aware that particle density and project textures will affect how you see the fire you're standing in. I keep my settings as low as I can manage while still having environmental awareness to move out of the fire. Running smooth all the time is very important to me, as a healer.
Be Pro In Game
I am not "pro", but I do emulate good players. If the encounter is new, head over to tankspot and watch the videos. Knowing the chaotic parts of a fight and being prepared can go a long way towards combatting low FPS. During a raid, your max FPS will be at max range, especially during an adds phase or if the boss has crazy animations. For fights where you have control over your movement, use it to your advantage and get away from the action. I am less likely to die from Lady D's DnD if 1. I know its coming, and 2. I'm not standing anywhere near anyone else (I actually have yet to die from DnD, but my computer does slow down when I'm in goo). While the argument can be made that's important for anyone regardless of computer spec, it's doubly important for those of us who know we're going to have a performance spike when goings get tough.
As a holy paladin, dealing with low FPS isn't too hard. Once I know the encounter, I can keep casting for the damage I expect my tanks to take, even if my UI isn't updating as fast as I'd like. It may translate into more overheal, but, uhm, we're holy paladins. Less than 50% overheal hasn't happened for me since I was progressing in heroics. That was a year ago! I also have to keep a close eye on my countdowns for Sacred Shield and Beacon - during a crazy part of the fight, the countdown might not even show on Healbot. If I know an add phase or spikey part of the fight is coming soon, I'll refresh those early instead of get stuck without them. When I play my druid or my priest, there are also things I can do to plan ahead for these performance spikes - bubbles last 30 seconds, and hots have predictable durations. It may not be the best, but it's the best I can do with the resources I have.
If you still just can't handle a 25-man environment, you can also try focusing on 10 mans. The low FPS I experience during 25's becomes easier to handle after I learn an encounter on 10, especially once I can find the best place for me to position. There still might be fights that are harder than others simply because of performance issues on an older computer (Ulduar comes to mind as the worst for me, so far). It takes a bit of honesty, especially if you feel you can't do your job just because you aren't blessed with the latest and greatest computer. However, you don't need the latest and greatest computer to be a competent healer. You just have to get your optimal UI going and make sure to use and take care of the resources you have.