OK, its coming back to me now... how many savegames do you have? As I recall it got slower and slower with each copy made... its fastest with only the autosave db or maybe one or two other saved campaigns (this was on my old 233MHz with a 4GB HDD).
I'm going to test a db clean on a singleplayer savegame...
EDIT: well I'll be dipped!!!
....
DarkElf's db cleaner works on the singleplayer game... (EDDBEDIT did not though) instructions:
put a copy of the exe in the zip linked above in the autosave folder that you want to clean
found in your game folder under: \MetaAssets\db\saves\savename
e.g. my test db was: C:\Program Files\Taldren Software Inc\Starfleet Command Orion Pirates\MetaAssets\db\saves\UAW Dominion 01
(I only ran it one turn and did not run any missions though - it was snappy over a number of movements and generated missions quickly)
double click the db cleaner exe... let it run. read the output.
delete the original sds, rename the extension of the output file to sds,
delete the cleaner exe,
copy the whole contents of that autosave folder (4 files) to the root of the db folder (\MetaAssets\db)
e.g for my test: C:\Program Files\Taldren Software Inc\Starfleet Command Orion Pirates\MetaAssets\db
restart OP load that savegame! Presto - db cleaned!
P.S. DarkElf you rock man! This exe has saved our butts so many times its not funny.
P.P.S. viking9, if this does not do it then there must be some other problem with your OP install or system, my singleplayer test ran fast before and after the db clean - not much difference really... (with only the autosave and one named save in the savegame list), so this may or may not solve your problem... also note that cleaning the single player db has not been done till now as far as I know, is untested and may produce unpredictable results... but at first glance it seems to work.
also note that before starting a new camaign the following may help:
In C:\Program Files\Taldren Software Inc\Starfleet Command Orion Pirates\MetaAssets\ServerProfiles\SinglePlayer\MetaMap.gf and Metamap.war try the following settings:
[Census]
TargetPopulationToEconomicRatio =0.002 // (0.02) This is the ratio of AI ships to current economy of an empire
OrionPopulationRatio =0.1 // (0.15) This is the population ratio for orion pirates.
MonsterPopulationRatio =0.005 // (0.025) This is the poplation ratio of Monsters.
StandardAIBPV =100 //Default AI BPV
MaxAIEcoBonusBPV =1.5 // Higher number will make bigger AI ships for losing empires
MinFuzzAIBPV =0.57 //Minimum random AI bpv level 0.3 = 30% less
MaxFuzzAIBPV =3.0 //Maximum random AI bpv level 2.0 = twice base
ChanceForTwoShips =0.1 //This is the chance for 2 ships for an AI
ChanceForThreeShips =0.04 //This is the chance for 3 ships for an AI
AttemptsToCreateAIInHomeHex =1 // Maximum AI to create in 1 turn
MaxAIsToCreatePerTurn =1 //How many AIs to try to create before giving up
MaxAIsToKillPerTurn =10 // (10) Maximum AIs to be killed in 1 turn before ending phase
AITurnOverRate =1 // (1)
MaxBattlesPerTurn =1//Maximum number AI battles in a turn before ending phase
CreateAIFrequency =1 // How many AIs to create a second, untill goal level reached
KillAIFrequency =1 // How many AIs to kill a second, untill goal level reached
InitalAILevel =100 // How many AI's to create before game starts
MaxAIsPerEmpire =1 // ( -1 ) Create a fixed number of AIs per empire. -1 means not to use a fixed number.
and under [Battle] add:
AllowAIToTakeHexes=0
These settings are for D2 servers and essentially minimise AI activity, you can try them but I'm not sure they will work on the single player game. Again, any of these changes will only work on a new campaign.
I highly reccomend you try a fresh OP install and install the Enhancement pack 3, it rocks... has all the stuff you need. In particular, the single player gfs are tweaked for better performance. Pestalence has that covered and can probably tell you more if you just want to try editng the singleplayer gfs.