diff --git a/src/codegen/compile.ml b/src/codegen/compile.ml
index 68db1f394c6..68041a72bd2 100644
--- a/src/codegen/compile.ml
+++ b/src/codegen/compile.ml
@@ -6583,7 +6583,7 @@ module MakeSerialization (Strm : Stream) = struct
 
     (* interval for checking instruction counter *)
     let idl_limit_interval = 32l (* TUNE *)
-    let idl_limit = 50_000_000L (* TUNE *)
+    let idl_limit_factor = 200L (* TUNE *)
     let idl_pseudo_cost = 100L (* TUNE *)
 
     let idl_instruction_counter env =
@@ -6604,11 +6604,15 @@ module MakeSerialization (Strm : Stream) = struct
         G.i (Binary (Wasm.Values.I64 I64Op.Add)) ^^
         set_pseudo_instruction_counter env
 
-    let reset_instruction_limit env get_rel_buf_opt =
+    let reset_instruction_limit env get_blob get_rel_buf_opt =
       get_rel_buf_opt ^^
       G.if0 begin (* Candid deserialization *)
         idl_instruction_counter env ^^
-        compile_const_64 idl_limit ^^
+        get_blob ^^
+        Blob.len env ^^
+        G.i (Convert (Wasm.Values.I64 I64Op.ExtendUI32)) ^^
+        compile_const_64 idl_limit_factor^^
+        G.i (Binary (Wasm.Values.I64 I64Op.Mul)) ^^
         G.i (Binary (Wasm.Values.I64 I64Op.Add)) ^^
         set_instruction_limit env
       end
@@ -8079,7 +8083,7 @@ module MakeSerialization (Strm : Stream) = struct
         get_typtbl_ptr ^^ load_unskewed_ptr ^^ Registers.set_typtbl env ^^
         get_maintyps_ptr ^^ load_unskewed_ptr ^^ Registers.set_typtbl_end env ^^
         get_typtbl_size_ptr ^^ load_unskewed_ptr ^^ Registers.set_typtbl_size env ^^
-        Registers.reset_instruction_limit env get_rel_buf_opt
+        Registers.reset_instruction_limit env get_blob get_rel_buf_opt
       end ^^
 
       (* set up a dedicated read buffer for the list of main types *)
diff --git a/test/bench/ok/bignum.drun-run-opt.ok b/test/bench/ok/bignum.drun-run-opt.ok
index 275dce6b630..789680e4738 100644
--- a/test/bench/ok/bignum.drun-run-opt.ok
+++ b/test/bench/ok/bignum.drun-run-opt.ok
@@ -2,5 +2,5 @@ ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a000000000000000001
 ingress Completed: Reply: 0x4449444c0000
 debug.print: {cycles = 2_512_723; size = +59_652}
 ingress Completed: Reply: 0x4449444c0000
-debug.print: {cycles = 107_695_540; size = +1_817_872}
+debug.print: {cycles = 107_695_543; size = +1_817_872}
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/bignum.drun-run.ok b/test/bench/ok/bignum.drun-run.ok
index 964db58e9dd..4179f01800a 100644
--- a/test/bench/ok/bignum.drun-run.ok
+++ b/test/bench/ok/bignum.drun-run.ok
@@ -2,5 +2,5 @@ ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a000000000000000001
 ingress Completed: Reply: 0x4449444c0000
 debug.print: {cycles = 2_619_856; size = +59_652}
 ingress Completed: Reply: 0x4449444c0000
-debug.print: {cycles = 107_890_493; size = +1_817_872}
+debug.print: {cycles = 107_890_497; size = +1_817_872}
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/run-drun/idl-limits-fine.mo b/test/run-drun/idl-limits-fine.mo
new file mode 100644
index 00000000000..30287a2d086
--- /dev/null
+++ b/test/run-drun/idl-limits-fine.mo
@@ -0,0 +1,39 @@
+import Region "stable-region/Region";
+import Prim "mo:prim";
+
+// shows that we can decode up to 15MB of coarse grained data before
+// exceeding the candid decoding limit
+actor {
+
+   let page : [Nat16] =
+   Prim.Array_tabulate<Nat16>(65536/4, func i {
+       Prim.natToNat16(i)});
+
+   var cnt = 0;
+   label l while (cnt < 64) {
+     let a = Prim.Array_tabulate<[Nat16]>(cnt*16, func i {page});
+     let b = to_candid (a);
+     if (b.size() > 10_000_000)  break l;
+     Prim.debugPrint(debug_show {bytes=b.size()});
+     let c1 = Prim.performanceCounter(0);
+     let ?_ = from_candid b : ?[[Nat16]];
+     let c2 = Prim.performanceCounter(0);
+     let diff = c2 - c1;
+     Prim.debugPrint(debug_show {
+       bytes = b.size();
+       MB = cnt;
+       instrs = diff;
+       instr_per_byte = Prim.nat64ToNat diff / b.size()
+     });
+     cnt += 1;
+   };
+
+}
+
+//SKIP run-low
+//SKIP run-ir
+//SKIP run
+//SKIP ic-ref
+
+
+
diff --git a/test/run-drun/idl-limits.mo b/test/run-drun/idl-limits.mo
index a1c0eeb19a5..83f7f58a545 100644
--- a/test/run-drun/idl-limits.mo
+++ b/test/run-drun/idl-limits.mo
@@ -11,11 +11,21 @@ actor {
    let page = Region.loadBlob(r, 0, Prim.nat64ToNat(pages*65536-1));
 
    var cnt = 0;
-   while (cnt < 32) {
+   label l while (cnt < 256) {
      let a = Prim.Array_tabulate<Blob>(cnt*16, func i {page});
      let b = to_candid (a);
+     if (b.size() > 10_000_000)  break l;
+     Prim.debugPrint(debug_show {bytes=b.size()});
+     let c1 = Prim.performanceCounter(0);
      let ?_ = from_candid b : ?[Blob];
-     Prim.debugPrint(debug_show {MB=cnt});
+     let c2 = Prim.performanceCounter(0);
+     let diff = c2 - c1;
+     Prim.debugPrint(debug_show {
+       bytes = b.size();
+       MB = cnt;
+       instrs = diff ;
+       instr_per_byte = Prim.nat64ToNat diff / b.size()
+     });
      cnt += 1;
    };
 
diff --git a/test/run-drun/ok/idl-limits-fine.drun-run.ok b/test/run-drun/ok/idl-limits-fine.drun-run.ok
new file mode 100644
index 00000000000..38bed358d0d
--- /dev/null
+++ b/test/run-drun/ok/idl-limits-fine.drun-run.ok
@@ -0,0 +1,42 @@
+ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
+debug.print: {bytes = 12}
+debug.print: {MB = 0; bytes = 12; instr_per_byte = 194; instrs = 2_331}
+debug.print: {bytes = 524_348}
+debug.print: {MB = 1; bytes = 524_348; instr_per_byte = 86; instrs = 45_447_595}
+debug.print: {bytes = 1_048_684}
+debug.print: {MB = 2; bytes = 1_048_684; instr_per_byte = 86; instrs = 90_892_859}
+debug.print: {bytes = 1_573_020}
+debug.print: {MB = 3; bytes = 1_573_020; instr_per_byte = 86; instrs = 136_338_331}
+debug.print: {bytes = 2_097_356}
+debug.print: {MB = 4; bytes = 2_097_356; instr_per_byte = 86; instrs = 181_783_595}
+debug.print: {bytes = 2_621_692}
+debug.print: {MB = 5; bytes = 2_621_692; instr_per_byte = 86; instrs = 227_228_859}
+debug.print: {bytes = 3_146_028}
+debug.print: {MB = 6; bytes = 3_146_028; instr_per_byte = 86; instrs = 272_674_331}
+debug.print: {bytes = 3_670_364}
+debug.print: {MB = 7; bytes = 3_670_364; instr_per_byte = 86; instrs = 318_119_595}
+debug.print: {bytes = 4_194_701}
+debug.print: {MB = 8; bytes = 4_194_701; instr_per_byte = 86; instrs = 363_564_898}
+debug.print: {bytes = 4_719_037}
+debug.print: {MB = 9; bytes = 4_719_037; instr_per_byte = 86; instrs = 409_010_162}
+debug.print: {bytes = 5_243_373}
+debug.print: {MB = 10; bytes = 5_243_373; instr_per_byte = 86; instrs = 454_455_426}
+debug.print: {bytes = 5_767_709}
+debug.print: {MB = 11; bytes = 5_767_709; instr_per_byte = 86; instrs = 499_900_898}
+debug.print: {bytes = 6_292_045}
+debug.print: {MB = 12; bytes = 6_292_045; instr_per_byte = 86; instrs = 545_346_162}
+debug.print: {bytes = 6_816_381}
+debug.print: {MB = 13; bytes = 6_816_381; instr_per_byte = 86; instrs = 590_791_426}
+debug.print: {bytes = 7_340_717}
+debug.print: {MB = 14; bytes = 7_340_717; instr_per_byte = 86; instrs = 636_236_690}
+debug.print: {bytes = 7_865_053}
+debug.print: {MB = 15; bytes = 7_865_053; instr_per_byte = 86; instrs = 681_682_162}
+debug.print: {bytes = 8_389_389}
+debug.print: {MB = 16; bytes = 8_389_389; instr_per_byte = 86; instrs = 727_127_426}
+debug.print: {bytes = 8_913_725}
+debug.print: {MB = 17; bytes = 8_913_725; instr_per_byte = 86; instrs = 772_572_690}
+debug.print: {bytes = 9_438_061}
+debug.print: {MB = 18; bytes = 9_438_061; instr_per_byte = 86; instrs = 818_018_162}
+debug.print: {bytes = 9_962_397}
+debug.print: {MB = 19; bytes = 9_962_397; instr_per_byte = 86; instrs = 863_463_218}
+ingress Completed: Reply: 0x4449444c0000
diff --git a/test/run-drun/ok/idl-limits-fine.tc.ok b/test/run-drun/ok/idl-limits-fine.tc.ok
new file mode 100644
index 00000000000..50d12e41c25
--- /dev/null
+++ b/test/run-drun/ok/idl-limits-fine.tc.ok
@@ -0,0 +1,5 @@
+idl-limits-fine.mo:19.10-19.12: warning [M0145], this pattern of type
+  ?[[Nat16]]
+does not cover value
+  null
+idl-limits-fine.mo:1.8-1.14: warning [M0194], unused identifier Region (delete or rename to wildcard `_` or `_Region`)
diff --git a/test/run-drun/ok/idl-spacebomb.drun-run.ok b/test/run-drun/ok/idl-spacebomb.drun-run.ok
index 2f5d216cca3..ca8b2fee94c 100644
--- a/test/run-drun/ok/idl-spacebomb.drun-run.ok
+++ b/test/run-drun/ok/idl-spacebomb.drun-run.ok
@@ -47,8 +47,7 @@ debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: ID
 debug.print: {function = "vec_null_subtyping"; hex = "4449444C016D7F0100FFFF3F"}
 debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: IDL error: exceeded instruction limit
 debug.print: {function = "vec_null_subtyping"; hex = "4449444C016D7F010080BF18"}
-debug.print: 40_775_934
-debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: assertion failed at idl-spacebomb.mo:40.5-40.41
+debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: IDL error: exceeded instruction limit
 debug.print: {function = "vec_reserved_subtyping"; hex = "4449444C016D7001008094EBDC03"}
 debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: IDL error: exceeded instruction limit
 debug.print: {function = "vec_reserved_subtyping"; hex = "4449444C016D70010080ADE204"}
@@ -56,8 +55,7 @@ debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: ID
 debug.print: {function = "vec_reserved_subtyping"; hex = "4449444C016D700100FFFF3F"}
 debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: IDL error: exceeded instruction limit
 debug.print: {function = "vec_reserved_subtyping"; hex = "4449444C016D70010080BF18"}
-debug.print: 40_775_934
-debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: assertion failed at idl-spacebomb.mo:40.5-40.41
+debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: IDL error: exceeded instruction limit
 debug.print: {function = "zero_sized_record_subtyping"; hex = "4449444C046C03007F010102026C0100706C006D0001038094EBDC03"}
 debug.print: IC0503: Canister rwlgt-iiaaa-aaaaa-aaaaa-cai trapped explicitly: IDL error: exceeded instruction limit
 debug.print: {function = "zero_sized_record_subtyping"; hex = "4449444C046C03007F010102026C0100706C006D00010380ADE204"}