I experienced the same (well, i have less fps), but it's old news - in native client i have the same issue in dx9 and thats why i go dx7. Even with everything you can turn off or set to lowest in-game.
But, when messing with config settings i was able to minimize the effect. Sadly, as i changed more than one value i am unable to recreate it right now. When i'll have time, i'll try to figure out where lies the problem (as it could be as simple as changing just one value).
[Battle]
bBlood=false
bDynamicBannerTransparency=false
bNoAttackingWhileJumpingMelee=false
bNoAttackingWhileJumpingRanged=false
bNoJumpingWhileAttack=false
bNoJumpingWhileAttackingMelee=false
bNoJumpingWhileAttackingRanged=true
bShowAttackDirection=true
bShowReticle=true
bWeaponTrails=true
bWeaponsCollideWithGround=true
fAirFrictionArrow=0.003000
fAirFrictionBullet=0.002000
fBattleSize=0.342200
fBloodMultiplier=2.000000
fBluntReduceFactor=0.750000
fBluntSoakFactor=0.500000
fBonusDamageToPropsFactor=1.100000
fBrokenShieldPruneTime=180.000000
fCouchedDamageToPropsFactor=0.200000
fCouchedLanceDamageMultiplier=0.650000
fCrushthroughThreshold=2.400000
fCutReduceFactor=1.000000
fCutSoakFactor=0.800000
fDamageToFriends=1.000000
fDamageToSelf=0.500000
fDroppedItemPruneTime=180.000000
fDynamicBannerTransparencyMaxDistance=600.000000
fDynamicBannerTransparencyMinDistance=400.000000
fExtraReduceFactor=1.000000
fExtraSoakFactor=1.000000
fFallDamageMultiplier=1.000000
fFirstPersonFieldOfView=75.000000
fGhostModeCameraAcceleration=25.000000
fGhostModeCameraDamping=5.000000
fGhostModeCameraMaxSpeed=10.000000
fHorseChargeDamageMultiplier=1.000000
fHorseJumpCooldown=4.000000
fInterruptThreshold=1.000000
fJumpCooldown=2.000000
fKickCooldown=1.800000
fMaxActionProgressForAllyCollision=1.000000
fMeleeDamageSpeedPower=2.000000
fMinActionProgressForAllyCollision=0.000000
fMinInflictedDamageForHighDamageHit=9.000000
fMissileDamageSpeedPower=1.900000
fMissileItemPruneTime=180.000000
fPierceReduceFactor=0.500000
fPierceSoakFactor=0.650000
fRangedDamageToPropsFactor=0.100000
fShieldPenetrationFactor=3.000000
fShieldPenetrationOffset=30.000000
fStrafeCooldown=0.450000
fThirdPersonFieldOfView=75.000000
iAttackControl=2
iBannerMode=2
iBannerOutlineMode=1
iBloodStains=0
iCombatSpeed=2
iDefendControl=0
iDynamicBannerTransparencyMaxAlpha=255
iDynamicBannerTransparencyMinAlpha=165
iFixedBannerTransparencyAlpha=215
iFixedBannerTransparencyOutlineAlpha=205
iHorseCameraMode=2
iLanceControl=0
iMaxNumCorpses=0
iMaxNumPrunableMissionObjects=500
iMaxNumRagdolls=0
iMinSoakedDamageForHighArmorHit=14
iNumWalkSamplePoints=8
uBannerOutlineColorEnemy=0xff0000
uBannerOutlineColorFriendly=0xff00
uBannerOutlineColorNeutral=0xff
vStickItemToLeftHandOffset=0.000000,-0.370000,-0.040000
[BattleAi]
iMinNumAgentsForNavMeshReuse=12
iReduceBattleAi=2
[Campaign]
bSkipTutorial=false
fDayEndHour=20.000000
fDayStartHour=4.000000
fHeroExperienceMultiplier=2.000000
fHeroHealingFactor=1.000000
fHeroWoundedThreshold=15.000000
fMainPartyHeroHealingFactor=1.000000
fMainPartyRegularHealingFactor=1.000000
fMapCameraMaxZoom=175.000000
fMapCameraMinZoom=3.500000
fMapRiverDirection=140.000000
fMapSeaDirection=-40.000000
fMapSeaWaveRotation=300.000000
fPlayerExperienceMultiplier=2.000000
fPlayerHealingFactor=1.000000
fPlayerWoundedThreshold=5.000000
fRegularExperienceMultiplier=3.000000
fRegularHealingFactor=1.000000
fSpottingMultiplier=6.500000
fTimeMultiplier=0.250000
fTrackSpottingMultiplier=0.800000
iBaseCompanionLimit=20
iLeadershipSkillBonus=3
iPrisonerManagementSkillBonus=5
vMapCameraMaxPosition=180.000000,145.000000
vMapCameraMinPosition=-180.000000,-145.000000
vMapRiverSpeed=0.010000,-0.010000
vMapSeaSpeed=0.020000,-0.020000
[CampaignAi]
iReduceCampaignAi=2
[DedicatedServer]
bAutoRestartOnCrash=true
bLogChat=true
bLogConnects=true
bLogDisconnects=true
bLogKills=true
bLogTeamChat=true
cLogSeparatorChar=,
fMinTimeForSuccessfulAutoRestart=120.000000
iMaxNumFailedAutoRestarts=5
[FaceGenerator]
bUseLowVariationCache=true
[FakeCharacterShadows]
bFakeCharacterShadows=false
bFakeCharacterShadowsHighQuality=false
fFakeCharacterShadowDepthBias=0.000200
fFakeCharacterShadowDetail=0.000000
fFakeCharacterShadowSlopeScaledDepthBias=2.000000
iFakeCharacterShadowTextureSize=256
sFakeCharacterShadowShader=shadow_shader
sFakeCharacterShadowShaderHighQuality=shadow_shader_new
uFakeCharacterShadowColor=0xff000915
[Flora]
fFloraDegradeDistance=75.000000
fGrassDensity=0.000000
fGrassMipMapLodBias=-1.000000
iFloraLod=3
iFloraShadows=0
iGrassMagFilter=2
iGrassMaxAnisotropy=4
iGrassMinFilter=3
iGrassMipFilter=2
[Font]
bFontAnisotropicFiltering=true
[General]
bDontBurnCpuCycles=true
bFirstRun=false
bHasCustomBattle=false
bHasFirearms=false
bHasMultiplayer=true
bHasSingleplayer=false
bHasTutorial=false
bInputLagOptimization=true
bPauseWhenMinimized=false
bPreventLowFrameLimitInputLag=true
bShowFrameRate=true
bSuppressPerformanceWarnings=true
bSuppressScriptErrors=false
bSuppressWarnings=false
iMaxFrameRate=100
iNumHints=0
iScreenshotFormat=1
sCoreResources=crpg_beta_core_shaders,crpg_beta_core_textures,crpg_beta_core_materials,core_ui_meshes,core_pictures
sIntroVideos=
[Graphics]
bAutoAdjustAspectRatio=true
bAutoAdjustFullscreenResolution=false
bDynamicMeshBatching=true
bForceVSync=false
bInstancing=false
bMaximized=true
bOnDemandTextures=false
bUseDirect3D9ExIfAvailable=true
bWindowed=false
fGamma=2.200000
fOnDemandTextureCheckPeriod=10.000000
fOnDemandTextureForceCheckPeriod=60.000000
iAnisotropicFiltering=0
iCubeMapMagFilter=2
iCubeMapMaxAnisotropy=0
iCubeMapMinFilter=2
iCubeMapMipFilter=2
iDiffuseMapMagFilter=1
iDiffuseMapMaxAnisotropy=0
iDiffuseMapMinFilter=1
iDiffuseMapMipFilter=1
iDisplayHeight=768
iDisplayWidth=1024
iEnvironmentMapMagFilter=1
iEnvironmentMapMaxAnisotropy=0
iEnvironmentMapMinFilter=1
iEnvironmentMapMipFilter=1
iFullscreenDisplayHeight=0
iFullscreenDisplayWidth=0
iGraphicsBufferLockFailThreshold=100
iIndexBufferSizeDynamic=262144
iIndexBufferSizeStatic=1310720
iInitialNumBufferedInstances=4116
iMaxNumAutoBatchMeshVertices=300
iMaxNumAutoBatchSkinnedMeshVertices=700
iMaxNumBatchedMeshVertices=1000
iMaxNumBufferedInstances=32768
iMaximumFrameLatency=1
iNormalMapMagFilter=0
iNormalMapMaxAnisotropy=0
iNormalMapMinFilter=0
iNormalMapMipFilter=0
iOnDemandTextureCheckThreshold=1000
iOnDemandTextureTimeout=12000000
iPreset=0
iShaderQuality=0
iSpecularMapMagFilter=0
iSpecularMapMaxAnisotropy=0
iSpecularMapMinFilter=0
iSpecularMapMipFilter=0
iTextureQuality=0
iVertexBufferSizeNormalMapDynamic=65536
iVertexBufferSizeNormalMapSkinningDynamic=65536
iVertexBufferSizeNormalMapSkinningStatic=131072
iVertexBufferSizeNormalMapStatic=131072
iVertexBufferSizeRegularDynamic=65536
iVertexBufferSizeRegularStatic=131072
iVertexBufferSizeSkinningDynamic=65536
iVertexBufferSizeSkinningStatic=131072
iVertexBufferSizeSpecialDynamic=32768
iVertexBufferSizeSpecialStatic=65536
iWindowedDisplayHeight=768
iWindowedDisplayWidth=1024
[Http]
iConnectTimeout=6000
iMaxNumRetries=3
iReceiveTimeout=4000
iResolveTimeout=6000
iSendTimeout=4000
sUserAgent=Mount Blade HTTP
[Input]
bInvertMouse=false
fMouseSensitivity=0.942538
fMouseXScale=1.000000
fMouseYScale=1.500000
[Log]
bAutoFlushLog=true
bBackupOnExit=true
iMaxNumStoredLogs=25
sLogPath=crpg_beta_log.txt
sStoredLogDirectory=Logs
[Messages]
bShowCasualties=true
bShowDamage=false
bShowExperienceGain=false
bShowMultiplayerChat=true
bShowMultiplayerTeamChat=true
bShowProficiencyGain=true
bShowScreenshotPath=true
bShowShotDifficulty=false
iMultiplayerKills=2
uMultiplayerChatColor=0xffcccccc
uMultiplayerTeamChatColor=0xff8888cc
[Network]
bHttpServerQueries=false
bLoopbackServer=false
bSecureMasterServerConnection=false
fPlayerActivityTimeout=20.000000
fPlayerInfoRequestActivityTimeout=3.000000
fServerActivityTimeout=20.000000
fServerInfoRequestActivityTimeout=3.000000
iDefaultPort=7240
iMaxNumServerSearchConnections=16
iUdpReceiveBufferSize=262144
iUdpSendBufferSize=262144
sAddress=// IP address of the server (empty for ANY)
[ParticleSystems]
bParticleSystems=false
iParticleSystemMaxNumMeshVertices=32000
iParticleSystemMaxNumRenderedParticles=4500
[Physics]
bAllBodiesAreMoveable=false
bRagdollHeadshots=false
fMaxDeltaTimeStep=0.025000
fMaxSlowMotionDeltaTimeStep=0.005000
fRagdollInactivePurgeTime=1.000000
fRagdollOnGroundPurgeTime=10.000000
fRagdollPurgeTime=30.000000
[PostFX]
bAutoExposure=false
bDepthEffects=false
iFxaa=0
iHighDynamicRange=0
iPostProcess=0
[Reflections]
iReflectionsMagFilter=0
iReflectionsMaxAnisotropy=0
iReflectionsMinFilter=0
iReflectionsMipFilter=0
iReflectionsMode=0
iReflectionsTextureSize=256
[Scene]
bSunFlare=false
fCharacterDetail=0.000000
sSunFlareMaterial=flare
sSunFlareMesh=sample_flare
[ServerList]
iDeadFavoritesPurgeTime=604800
iDeadFavoritesPurgeTries=7
[ShadowMap]
bShadowMap=false
fShadowMapDepthBias=0.000200
fShadowMapSlopeScaledDepthBias=2.000000
iShadowMapNumPasses=2
iShadowMapTextureSize=256
sShadowMapShader=shadow_shader
[Sound]
bDisableFrequencyVariation=false
bDisableMusic=false
bDisableSound=false
bDistanceFilter=true
bFastOcclusion=true
bHrtfFilter=true
bOcclusion=false
bOcclusionFilter=false
bUseWinmm=false
bWasapiExclusive=false
fDistancePriorityFactor=0.100000
fMusicVolume=0.000000
fSoundVolume=0.424700
iMaxNumChannels=64
iMaxNumVirtualChannels=200
[TerrainGenerator]
fOuterTerrainHeightOffset=1.500000
fOuterTerrainMaxBlendDistance=100.000000
iMaxNumFloraInstances=1024
iMaxNumFloraTypes=32
iMaxNumGrassInstances=262144
iMaxNumGrassTypes=32
iMaxNumTreeInstances=1024
iMaxNumTreeTypes=32
[Threads]
bThreadedIndexBufferWrites=false
bThreadedLogger=false
bThreadedNetwork=true
bThreadedOnDemandTextures=false
bThreadedRenderer=false
bThreadedSkeletalAnimation=false
bThreadedVertexBufferWrites=false
iAsyncRenderCallsCriticalSectionSpinCount=0
iNetworkCriticalSectionSpinCount=0
iNumTaskThreads=0
iRenderBufferCriticalSectionSpinCount=0
iRenderThreadCriticalSectionSpinCount=0
iTaskCriticalSectionSpinCount=0
iTextureCreatorCriticalSectionSpinCount=0
iTextureLoaderCriticalSectionSpinCount=0