diff --git a/.gitignore b/.gitignore
index a85d0dd2..153e7275 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,3 +20,4 @@ tags
 env-riscv-tools.sh
 env-esp-tools.sh
 .bloop/
+.bsp/
diff --git a/.sbtopts b/.sbtopts
deleted file mode 100644
index 2358d787..00000000
--- a/.sbtopts
+++ /dev/null
@@ -1,2 +0,0 @@
--Dsbt.sourcemode=true
--Dsbt.workspace=$PWD/tools
diff --git a/build.sbt b/build.sbt
index 01655abc..1132dde1 100644
--- a/build.sbt
+++ b/build.sbt
@@ -81,7 +81,7 @@ lazy val chiselLibDeps = (chiselRef / Keys.libraryDependencies)
 //   keeping scalaVersion in sync with chisel3 to the minor version
 lazy val chiselPluginLib = "edu.berkeley.cs" % "chisel3-plugin" % chiselVersion cross CrossVersion.full
 
-val firrtlVersion = "1.4-SNAPSHOT"
+val firrtlVersion = "1.4.+"
 lazy val firrtlRef = ProjectRef(workspaceDirectory / "firrtl", "firrtl")
 lazy val firrtlLib = "edu.berkeley.cs" %% "firrtl" % firrtlVersion
 //lazy val firrtlLibDeps = (firrtlRef / Keys.libraryDependencies) // TODO: Won't work because of antlr plugin
diff --git a/common.mk b/common.mk
index 80565a37..4f632a26 100644
--- a/common.mk
+++ b/common.mk
@@ -63,7 +63,7 @@ SCALA_SOURCES = $(call lookup_srcs,$(SOURCE_DIRS),scala)
 VLOG_SOURCES = $(call lookup_srcs,$(SOURCE_DIRS),sv) $(call lookup_srcs,$(SOURCE_DIRS),v)
 # This assumes no SBT meta-build sources
 SBT_SOURCE_DIRS = $(addprefix $(base_dir)/,generators sims/firesim/sim tools)
-SBT_SOURCES = $(call lookup_srcs,$(SBT_SOURCE_DIRS),sbt) $(base_dir)/build.sbt $(base_dir)/project/plugins.sbt
+SBT_SOURCES = $(call lookup_srcs,$(SBT_SOURCE_DIRS),sbt) $(base_dir)/build.sbt $(base_dir)/project/plugins.sbt $(base_dir)/project/build.properties
 
 #########################################################################################
 # Bloop Project Definitions
@@ -209,7 +209,7 @@ ifneq ($(filter run% %.run %.out %.vpd %.vcd,$(MAKECMDGOALS)),)
 endif
 
 #######################################
-# Rules for building DRAMSim2 library #
+# Rules for building DRAMSim2 library
 #######################################
 
 dramsim_dir = $(base_dir)/tools/DRAMSim2
@@ -218,14 +218,18 @@ dramsim_lib = $(dramsim_dir)/libdramsim.a
 $(dramsim_lib):
 	$(MAKE) -C $(dramsim_dir) $(notdir $@)
 
-#######################################
-# Helper to run SBT                   #
-#######################################
+################################################
+# Helper to run SBT or shutdown the SBT server
+################################################
 
 .PHONY: launch-sbt
 launch-sbt:
 	cd $(base_dir) && $(SBT)
 
+.PHONY: launch-sbt
+shutdown-sbt:
+	cd $(base_dir) && $(SBT) shutdown
+
 #########################################################################################
 # print help text
 #########################################################################################
diff --git a/project/build.properties b/project/build.properties
index 0837f7a1..7de0a938 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.3.13
+sbt.version=1.4.4
diff --git a/variables.mk b/variables.mk
index 42dc48c5..73918376 100644
--- a/variables.mk
+++ b/variables.mk
@@ -146,21 +146,22 @@ sim_common_files       ?= $(build_dir)/sim_files.common.f
 # java arguments used in sbt
 #########################################################################################
 JAVA_HEAP_SIZE ?= 8G
-JAVA_ARGS ?= -Xmx$(JAVA_HEAP_SIZE) -Xss8M -XX:MaxPermSize=256M
+JAVA_OPTS ?= -Xmx$(JAVA_HEAP_SIZE) -Xss8M -XX:MaxPermSize=256M
 
 #########################################################################################
 # default sbt launch command
 #########################################################################################
-# Running with sbt-launch.jar doesn't read .sbtopts by default
-# # Set if the file exists (if it exists, we're building chisel3 and firrtl from source)
-sbtopts_file := $(base_dir)/.sbtopts
-ifneq (,$(wildcard $(sbtopts_file)))
-	SBT_OPTS ?= $(shell cat $(sbtopts_file))
+# by default build chisel3/firrtl and other subprojects from source
+override SBT_OPTS += -Dsbt.sourcemode=true -Dsbt.workspace=$(base_dir)/tools
+
+ifdef ENABLE_SBT_THIN_CLIENT
+# enabling speeds up sbt loading
+# however if build.sbt changes are done you need to
+#   "shutdown" the server (shutdown-sbt target) to reload build.sbt changes
+SBT_CLIENT_FLAG = --client
 endif
 
-SCALA_VERSION=2.12.10
-SCALA_VERSION_MAJOR=$(basename $(SCALA_VERSION))
-SBT ?= java $(JAVA_ARGS) -jar $(ROCKETCHIP_DIR)/sbt-launch.jar $(SBT_OPTS)
+SBT ?= java $(JAVA_OPTS) -jar $(ROCKETCHIP_DIR)/sbt-launch.jar $(SBT_OPTS) $(SBT_CLIENT_FLAG)
 
 BLOOP ?= bloop
 BLOOP_CONFIG_DIR ?= $(base_dir)/.bloop
@@ -183,7 +184,7 @@ define run_scala_main
 endef
 else
 define run_scala_main
-	cd $(base_dir) && $(SBT) "project $(1)" "runMain $(2) $(3)"
+	cd $(base_dir) && $(SBT) ";project $(1); runMain $(2) $(3)"
 endef
 endif