I recently removed my Hamidon raid costume as it didn't seem to be needed anymore - I suppose I could ditch my halloween outfit and bring it back 
Welcome to the forums, by the way 
@Golden Girl
City of Heroes comics and artwork
The main difference between the Hami raids & the Rikti invasions would be when facing Hami everyone has the majority of their toggles off (except mez) (untyped damage, so no protection) when doing a Rikti invasion everyone has all toggles on.
This means a lot more graphics on screen at any one time. While I agree that a raid costume will help, it won't totally solve the problem.
If we did pre i9 Hami raids with toggles on we would all have been lagged to death, even with Hami costumes. There is no way the numbers attending an Invasion can be reduced. The only posibility i can see is if toggle animations are reduced in any areas where there are Invasions.
This may not be popular with people with high end comps, but would do a lot to solve the problem. Unfortunatly, the GM's may find this very hard to implement.
Well thats just my opinion 
Xtream
Oh & Welcome to the forums
50's -
Scrappers - Xtream & Ouroboros Enforcer. Controllers - Vanguard Phoenix, Midnight Protector & Mythical Illusion. Tanks - Stone Cold Sober. Blasters - Ultimate Solution & Crey Prototype. Defenders - Lucifer - Bound. Peacebringers - Xtream Justice. Masterminds - Xtream Malfunction. SoA - Arachnid Lord
One way to get round it might be to ask people to split the gathering point - in Kings Row for example, if half the Heroes went to Blue Steel, and half went to the station, it'd reduce the lag quite a bit.
@Golden Girl
City of Heroes comics and artwork
Ok, I'll probably get flamed for this (avoids all fire tanks and blasters..), however...
I have have noticed that when there is a large group of heroes doing the main Rikti Invasions (not the bombs bit), the graphical lag is terrible.
Here is a slight, though probably gonna be unpopular suggestion.. Why don't we creat/use 'raid' costumes like they do on the Hami raid? I've created one identical to Hami Raid Cossy but changed the chest emblem to an 'R' instead of an 'H'. I know that not everyone will be able to do this but if you can, it should cut down on the gfx lag peeps get. All those auras,wings etc can be bad for gfx lag when loads of peeps are fighting.
For example, During a recent Atlas Park invasion, there were so many Heroes fighting that I personally was at 1-2, sometimes 3 fps. also 20s delays on power activations.
Costume of Choice (one I use).
Head:
Full Helmet - Tech Helmet - No Details
Upper Boddy:
Tights - Muscular
Shoulders - None
Belt - None
Gloves - Smooth - Full.
Lower Body:
Legs - Tights
Boots - Smooth Tights
Black Costume as main colour.
Colour of choice for following.
Chest - Stripe1
Chest Detail - 'R'
Gloves - Stripe
Pants - Stripe1
Boots - Stripe
Of course, you don't HAVE to use the above but it would help those of us who don't have, and can't currently afford the latest PC rigs