[One (M9) Android Development] jollywhitefoot:
Hey Lee, I haven't experienced any lag issues since upgrading to Marshmallow in December. For about a month i was full stock, rooted developed edition, then for the past month I've been running MaximusHD, with momentary breaks to flash your rom and try to test AT&T for you (more on that later). The only lag that I can say I've experienced was last night when I flashed the new ElementalX kernel. After flashing the kernel, chrome started stuttering pretty badly, but I went into Flar's ElementalX app and the CPU governor was set to interactive. Once I set it to ElementalX Governor all was immediately good again. If I have time this week, I'll try flashing your latest rom with flar's kernel to see how that affects lag.

Is the lag people are experiencing reproducible? Judging by your frustration, it seems to be pretty random.

Anyway, about AT&T..For VoLTE to work some of your AT&T settings are a little off (maybe you left these options off intentionally?). I haven't been able to successfully test this, and I'm not sure if the issue is that people I'm calling and testing with aren't in a VOLTE area or if it just doesn't work, period (for ATT volte to work, both parties have to be in a volte area with the option on both phones enabled). Or maybe it won't work until the ATT firmware is released. Either way, I know the settings below are needed for any chance of it working.

ACC\default.xml

<app name="Phone">
<item type="integer" name="advanced_calling_ui_version">2</item>
<item type="boolean" name="alternativeEccWay">false</item>
<item type="boolean" name="apply_4G_enhanced_service_generic_summary">false</item>
<item type="boolean" name="auto_answer_on_def">true</item>
<item type="boolean" name="callBarringDisabled">false</item>
<item type="boolean" name="CB_HIDE_OTHERS_BUTTON">false</item>
<item type="integer" name="cdmaNetBusyToneId">-1</item>
<item type="integer" name="cdmaNetBusyToneLengthMillis">5000</item>
<item type="string" name="customizeVoiceMailCarrierName"></item>
<item type="integer" name="delayOfAllowIncomingRing">300</item>
<item type="boolean" name="disableHearingAidsCdma">true</item>
<item type="boolean" name="disableHearingAidsWorldPhone">true</item>
<item type="boolean" name="disableVoiceMailNumber">false</item>
<item type="integer-array" name="discardMipValues">
<int>-1</int>
</item>
<item type="boolean" name="displaySimNotReadableNotification">false</item>
<item type="boolean" name="dualSimDataRoamingPreferredSlot">false</item>
<item type="boolean" name="enable_lifetime_calls">false</item>
<item type="boolean" name="enableHearingAidsGsm">true</item>
<item type="boolean" name="enableUpdateAttrPsensorStatusHandsFree">false</item>
<item type="boolean" name="fdnDisabled">false</item>
<item type="boolean" name="featureCdmaApnSettings">false</item>
<item type="boolean" name="featureCdmaCallForwarding">false</item>
<item type="boolean" name="featureCdmaCallWaiting">false</item>
<item type="boolean" name="featureCdmaLteApnSettings">false</item>
<item type="boolean" name="featureCdmaLteNetworkSelector">false</item>
<item type="boolean" name="featureCdmaPreferredRoaming">true</item>
<item type="boolean" name="featureCDMATtyMode">true</item>
<item type="boolean" name="featureDataWaringBootUp">false</item>
<item type="boolean" name="featureGlobalRoamingOptions">false</item>
<item type="boolean" name="featureGSMTtyMode">true</item>
<item type="boolean" name="featureHttpRedirect">false</item>
<item type="boolean" name="featureNotLogEmergencyNumber">true</item>
<item type="boolean" name="featurePco">false</item>
<item type="boolean" name="featurePlusCodeDialing">false</item>
<item type="boolean" name="featurePreferredNetworkOptionLteBoundCdmaGsm">false</item>
<item type="boolean" name="featureSupportVoiceRecording">true</item>
<item type="boolean" name="hideCellBroadcastSetting">false</item>
<item type="boolean" name="isNoneOrientationSensorDevices">false</item>
<item type="boolean" name="isWaterProof">false</item>
<item type="boolean" name="needChangedPhoneNoticationSummary">true</item>
<item type="boolean" name="onlyQueryMoCallLog">false</item>
<item type="integer" name="preferred_network_type_mode_style">7</item>
<item type="boolean" name="showAccumulatorCallButton">false</item>
<item type="boolean" name="showApnNameInsteadOfApnInNotification">false</item>
<item type="boolean" name="supportActionQuickBootPoweron">false</item>
<item type="boolean" name="supportCellBroadcase">false</item>
<item type="boolean" name="supportDataRoamButton">false</item>
<item type="boolean" name="supportHomePlusCodePrefixNumber">false</item>
<item type="boolean" name="supportNationalRoaming">false</item>
<item type="boolean" name="supportNlAlert">false</item>
<item type="boolean" name="supportPowerBackOff">false</item>
<item type="boolean" name="supportSemiEccCalls">false</item>
<item type="boolean" name="supportShowSimPinAcceptMessageToast">false</item>
<item type="boolean" name="SupportTGPreferredMode">false</item>
<item type="boolean" name="supportTurnAirPlaneModeByAlarm">false</item>
<item type="boolean" name="supportUserPreferredNetworkList">false</item>
<item type="boolean" name="supportVivoPtb">false</item>
[COLOR="Red"] <item type="boolean" name="voLteEnableAutoDomain">true</item>
<item type="boolean" name="voLteEnabled">true</item>
<item type="boolean" name="voLteEnableImsToggle">true</item>
<item type="boolean" name="voLteEnableMultitasking">true</item>
<item type="boolean" name="voLteForbidSsDuringE911">true</item>[/COLOR]
</app>
.......
<system>
<item type="boolean" name="build_to_preload">true</item>
<item type="integer" name="chipset">1</item>
<item type="integer" name="device_type">1</item>
<item type="integer" name="dual_sim_device_data_type">0</item>
<item type="string" name="extra_sense_version">7.0</item>
<item type="boolean" name="feature_auto_sim_switch">false</item>
<item type="boolean" name="for_nel">false</item>
<item type="boolean" name="front_flashlight">false</item>
<item type="boolean" name="has_its_on_ap">false</item>
<item type="boolean" name="has_three_modems">false</item>
<item type="boolean" name="have_front_camera">true</item>
<item type="boolean" name="is_gp">false</item>
<item type="boolean" name="isidda_device">false</item>
<item type="string" name="original_sense_version">7.0</item>
<item type="integer" name="radio_type">4</item>
<item type="integer" name="region">1</item>
<item type="string" name="sense_version">7.0</item>
<item type="boolean" name="single_modem_dsda_device">false</item>
<item type="integer" name="sku_id">6</item>
<item type="integer" name="sub_sku_id">0</item>
<item type="boolean" name="support_3lm">false</item>
<item type="boolean" name="support_beats_audio">false</item>
<item type="boolean" name="support_boomsound_effect">true</item>
<item type="boolean" name="support_cb_on_dual">false</item>
<item type="boolean" name="support_new_recent_apps_feature">true</item>
<item type="boolean" name="support_china_sense_feature">false</item>
<item type="boolean" name="support_china_sense_typeb_feature">false</item>
<item type="boolean" name="support_china_sense_typeb_new_feature">false</item>
<item type="boolean" name="support_dlna">true</item>
<item type="boolean" name="support_dual_lens">false</item>
<item type="boolean" name="support_dual_sim">false</item>
<item type="boolean" name="support_fingerprint">false</item>
<item type="boolean" name="support_hide_select_runtime">false</item>
<item type="boolean" name="support_ir">true</item>
<item type="boolean" name="support_lte">true</item>
<item type="boolean" name="support_sim_card">true</item>
<item type="boolean" name="support_SRLTE">false</item>
<item type="boolean" name="support_synccall">false</item>
[COLOR="Red"]<item type="string" name="support_volte">ir92</item>[/COLOR]
<item type="boolean" name="support_Wifioffload">false</item>
<item type="boolean" name="support_wimax">false</item>
<item type="boolean" name="use_stock_ui">false</item>
<item type="integer" name="vibration_duration">14</item>
<item type="boolean" name="wifi_only">false</item>
</system>

And for MNS\default.xml, AT&T supports 1M sms messages now. I think your file settings are old.

<module name="MessageConfig">
<function name="setting">
<set name="single">
<item name="SMS_Delivery_Report">false</item>
<item name="MMS_Delivery_Report">false</item>
<item name="MMS_Read_Report">false</item>
<item name="MMS_Auto_Retrieve">true</item>
<item name="MMS_Roaming_Auto_Retrieve">false</item>
<item name="MMS_Priority">Normal</item>
[COLOR="Red"] <item name="MMS_Msg_Size1">300K</item>
<item name="MMS_Msg_Size2">600K</item>
<item name="MMS_Msg_Size3">1M</item>
<item name="MMS_Msg_Size_Choose">1M</item>[/COLOR]
<item name="MMS_Received_Notify">true</item>
<item name="MMS_Play_Received_Notify">true</item>
<item name="MMS_Received_Viberation">true</item>
<item name="MMS_Sent_Notify">false</item>
<item name="MMS_Fail_Notify">true</item>
<item name="MMS_Play_Notify">true</item>
<item name="MMS_Notify_Sound">Default Ringtone</item>
<item name="MMS_Viberation">true</item>
<item name="MMS_Max_Recipient_Number">10</item>
<item name="SMS_Max_Recipient_Number">250</item>
<item name="SMS_Max_Concatenated_Number">5</item>
<item name="MMS_Max_Slide_Number">10</item>
<item name="MMS_Default_Slide_Duration">5000</item>
<item name="RECIPT_Show_Sent_Msg_History">true</item>
<item name="RECIPT_Show_Email_Address">false</item>
<item name="MSG_Preview_Line">1</item>
<item name="STORAGE_Del_Old_Msg">false</item>
<item name="STORAGE_Text_Msg_Limit">200</item>
<item name="STORAGE_MMS_Msg_Limit">20</item>
<item name="SMS_Wap_Push_Support">true</item>
<item name="SMS_Empty_Draft_Support">false</item>
<item name="SMS_To_Email_Support">true</item>
<item name="SMS_Email_Server_Number">6245</item>
<item name="SMS_Class_Zero_Save_Support">true</item>
<item name="SMS_Concatenated_Email_SMS">false</item>
<item name="SMS_Subject_Support">false</item>
<item name="SMS_SMSC_Editable">true</item>
<item name="SMS_Empty_SMS_Support">true</item>
<item name="SMS_Use_Device_Time">false</item>
<item name="SMS_Characters">true</item>
<item name="MMS_Retry_Policy">15,15,15,15,15,15</item>
<item name="MSG_General_CMAS_Support">true</item>
<item name="MSG_Use_Signature">false</item>
<item name="Display_message_on_screen">success_and_failure</item>
<item name="MMS_Show_All_Mixed_Text">false</item>
<item name="RECIPT_Input_Type_Number">false</item>
<item name="MMS_Force_Display_In_Slideshow">false</item>
<item name="MMS_Show_Restricted_Mode">false</item>
</set>
</function>
</module>

Anyway, like I said, I'm still trying to get it to work, but my job is getting in the way. Hopefully I'll have more time later in the week to play with this more.

Thanks and keep up the great work.