I think I've solved the slow down issue. Parameters can't be mixed with cvw_t and other types.

src/privileged/csrc.sv

@@ -30,17 +30,7 @@
 // and limitations under the License.
 ////////////////////////////////////////////////////////////////////////////////////////////////
 
-module csrc import cvw::*;  #(parameter cvw_t P,
+module csrc  import cvw::*;  #(parameter cvw_t P) (
-  MHPMCOUNTERBASE = 12'hB00,
-  MTIME = 12'hB01,               // this is a memory-mapped register; no such CSR exists, and access should fault
-  MHPMCOUNTERHBASE = 12'hB80,
-  MTIMEH = 12'hB81,               // this is a memory-mapped register; no such CSR exists, and access should fault
-  MHPMEVENTBASE = 12'h320,
-  HPMCOUNTERBASE = 12'hC00,
-  HPMCOUNTERHBASE = 12'hC80,
-  TIME  = 12'hC01,
-  TIMEH = 12'hC81
-) (
   input  logic             clk, reset,
   input  logic             StallE, StallM, 
   input  logic             FlushM, 
@@ -73,6 +63,16 @@ module csrc import cvw::*;  #(parameter cvw_t P,
   output logic             IllegalCSRCAccessM
 );
 
+  localparam MHPMCOUNTERBASE = 12'hB00;
+  localparam MTIME = 12'hB01;               // this is a memory-mapped register; no such CSR exists, and access should faul;
+  localparam MHPMCOUNTERHBASE = 12'hB80;
+  localparam MTIMEH = 12'hB81;               // this is a memory-mapped register; no such CSR exists, and access should fault
+  localparam MHPMEVENTBASE = 12'h320;
+  localparam HPMCOUNTERBASE = 12'hC00;
+  localparam HPMCOUNTERHBASE = 12'hC80;
+  localparam TIME          = 12'hC01;
+  localparam TIMEH = 12'hC81;
+
   logic [4:0]              CounterNumM;
   logic [P.XLEN-1:0]        HPMCOUNTER_REGW[P.COUNTERS-1:0];
   logic [P.XLEN-1:0]        HPMCOUNTERH_REGW[P.COUNTERS-1:0];

src/privileged/csri.sv

@@ -27,11 +27,7 @@
 // and limitations under the License.
 ////////////////////////////////////////////////////////////////////////////////////////////////
 
-module csri import cvw::*;  #(parameter cvw_t P,
+module csri import cvw::*;  #(parameter cvw_t P) (
-  MIE = 12'h304,
-  MIP = 12'h344,
-  SIE = 12'h104,
-  SIP = 12'h144) (
   input  logic              clk, reset, 
   input  logic              CSRMWriteM, CSRSWriteM,
   input  logic [P.XLEN-1:0]  CSRWriteValM,
@@ -46,6 +42,11 @@ module csri import cvw::*;  #(parameter cvw_t P,
   logic                     WriteMIPM, WriteMIEM, WriteSIPM, WriteSIEM;
   logic                     STIP;
 
+  localparam MIE = 12'h304;
+  localparam MIP = 12'h344;
+  localparam SIE = 12'h104;
+  localparam SIP = 12'h144;
+
   // Interrupt Write Enables
   assign WriteMIPM = CSRMWriteM & (CSRAdrM == MIP);
   assign WriteMIEM = CSRMWriteM & (CSRAdrM == MIE);

src/privileged/csrm.sv

@@ -31,45 +31,7 @@
 // and limitations under the License.
 ////////////////////////////////////////////////////////////////////////////////////////////////
 
-module csrm import cvw::*;  #(parameter cvw_t P,
+module csrm  import cvw::*;  #(parameter cvw_t P) (
-  // Machine CSRs
-  MVENDORID = 12'hF11,
-  MARCHID = 12'hF12,
-  MIMPID = 12'hF13,
-  MHARTID = 12'hF14,
-  MCONFIGPTR = 12'hF15,
-  MSTATUS = 12'h300,
-  MISA_ADR = 12'h301,
-  MEDELEG = 12'h302,
-  MIDELEG = 12'h303,
-  MIE = 12'h304,
-  MTVEC = 12'h305,
-  MCOUNTEREN = 12'h306,
-  MSTATUSH = 12'h310,
-  MCOUNTINHIBIT = 12'h320,
-  MSCRATCH = 12'h340,
-  MEPC = 12'h341,
-  MCAUSE = 12'h342,
-  MTVAL = 12'h343,
-  MIP = 12'h344,
-  MTINST = 12'h34A,
-  PMPCFG0 = 12'h3A0,
-  // .. up to 15 more at consecutive addresses
-  PMPADDR0 = 12'h3B0,
-  // ... up to 63 more at consecutive addresses
-  TSELECT = 12'h7A0,
-  TDATA1 = 12'h7A1,
-  TDATA2 = 12'h7A2,
-  TDATA3 = 12'h7A3,
-  DCSR = 12'h7B0,
-  DPC = 12'h7B1,
-  DSCRATCH0 = 12'h7B2,
-  DSCRATCH1 = 12'h7B3,
-  // Constants
-  ZERO = {(P.XLEN){1'b0}},
-  MEDELEG_MASK = 16'hB3FF,
-  MIDELEG_MASK = 12'h222 // we choose to not make machine interrupts delegable
-) (
   input  logic                    clk, reset, 
   input  logic                    UngatedCSRMWriteM, CSRMWriteM, MTrapM,
   input  logic [11:0]             CSRAdrM,
@@ -94,6 +56,44 @@ module csrm import cvw::*;  #(parameter cvw_t P,
   logic                           WriteMSCRATCHM, WriteMEPCM, WriteMCAUSEM, WriteMTVALM;
   logic                           WriteMCOUNTERENM, WriteMCOUNTINHIBITM;
 
+  // Machine CSRs
+  localparam MVENDORID = 12'hF11;
+  localparam MARCHID = 12'hF12;
+  localparam MIMPID = 12'hF13;
+  localparam MHARTID = 12'hF14;
+  localparam MCONFIGPTR = 12'hF15;
+  localparam MSTATUS = 12'h300;
+  localparam MISA_ADR = 12'h301;
+  localparam MEDELEG = 12'h302;
+  localparam MIDELEG = 12'h303;
+  localparam MIE = 12'h304;
+  localparam MTVEC = 12'h305;
+  localparam MCOUNTEREN = 12'h306;
+  localparam MSTATUSH = 12'h310;
+  localparam MCOUNTINHIBIT = 12'h320;
+  localparam MSCRATCH = 12'h340;
+  localparam MEPC = 12'h341;
+  localparam MCAUSE = 12'h342;
+  localparam MTVAL = 12'h343;
+  localparam MIP = 12'h344;
+  localparam MTINST = 12'h34A;
+  localparam PMPCFG0 = 12'h3A0;
+  // .. up to 15 more at consecutive addresses
+  localparam PMPADDR0 = 12'h3B0;
+  // ... up to 63 more at consecutive addresses
+  localparam TSELECT = 12'h7A0;
+  localparam TDATA1 = 12'h7A1;
+  localparam TDATA2 = 12'h7A2;
+  localparam TDATA3 = 12'h7A3;
+  localparam DCSR = 12'h7B0;
+  localparam DPC = 12'h7B1;
+  localparam DSCRATCH0 = 12'h7B2;
+  localparam DSCRATCH1 = 12'h7B3;
+  // Constants
+  localparam ZERO = {(P.XLEN){1'b0}};
+  localparam MEDELEG_MASK = 16'hB3FF;
+  localparam MIDELEG_MASK = 12'h222; // we choose to not make machine interrupts delegable
+
  // There are PMP_ENTRIES = 0, 16, or 64 PMPADDR registers, each of which has its own flop
   genvar i;
   if (P.PMP_ENTRIES > 0) begin:pmp

src/privileged/csrs.sv

@@ -28,20 +28,7 @@
 // and limitations under the License.
 ////////////////////////////////////////////////////////////////////////////////////////////////
 
-module csrs import cvw::*;  #(parameter cvw_t P,
+module csrs import cvw::*;  #(parameter cvw_t P) (
-  // Supervisor CSRs
-  SSTATUS = 12'h100,
-  SIE = 12'h104,
-  STVEC = 12'h105,
-  SCOUNTEREN = 12'h106,
-  SSCRATCH = 12'h140,
-  SEPC = 12'h141,
-  SCAUSE = 12'h142,
-  STVAL = 12'h143,
-  SIP= 12'h144,
-  STIMECMP = 12'h14D,
-  STIMECMPH = 12'h15D,
-  SATP = 12'h180) (
   input  logic             clk, reset, 
   input  logic             CSRSWriteM, STrapM,
   input  logic [11:0]      CSRAdrM,
@@ -62,6 +49,19 @@ module csrs import cvw::*;  #(parameter cvw_t P,
   output logic             STimerInt
 );
 
+  // Supervisor CSRs
+  localparam SSTATUS = 12'h100;
+  localparam SIE = 12'h104;
+  localparam STVEC = 12'h105;
+  localparam SCOUNTEREN = 12'h106;
+  localparam SSCRATCH = 12'h140;
+  localparam SEPC = 12'h141;
+  localparam SCAUSE = 12'h142;
+  localparam STVAL = 12'h143;
+  localparam SIP= 12'h144;
+  localparam STIMECMP = 12'h14D;
+  localparam STIMECMPH = 12'h15D;
+  localparam SATP = 12'h180;
   // Constants
   localparam ZERO = {(P.XLEN){1'b0}};
   localparam SEDELEG_MASK = ~(ZERO | {{P.XLEN-3{1'b0}}, 3'b111} << 9);

src/privileged/csru.sv

@@ -26,10 +26,7 @@
 // and limitations under the License.
 ////////////////////////////////////////////////////////////////////////////////////////////////
 
-module csru import cvw::*;  #(parameter cvw_t P,
+module csru import cvw::*;  #(parameter cvw_t P) (
-  FFLAGS = 12'h001,
-  FRM = 12'h002,
-  FCSR = 12'h003) (
   input  logic             clk, reset, 
   input  logic             InstrValidNotFlushedM,
   input  logic             CSRUWriteM,
@@ -43,6 +40,10 @@ module csru import cvw::*;  #(parameter cvw_t P,
   output logic             IllegalCSRUAccessM
 );
 
+  localparam FFLAGS = 12'h001;
+  localparam FRM = 12'h002;
+  localparam FCSR = 12'h003;
+
   logic [4:0]              FFLAGS_REGW;
   logic [2:0]              NextFRMM;
   logic [4:0]              NextFFLAGSM;